commit 0ebeea8ca8 upstream.
Given the legacy bpf_probe_read{,str}() BPF helpers are broken on archs
with overlapping address ranges, we should really take the next step to
disable them from BPF use there.
To generally fix the situation, we've recently added new helper variants
bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str().
For details on them, see 6ae08ae3de ("bpf: Add probe_read_{user, kernel}
and probe_read_{user,kernel}_str helpers").
Given bpf_probe_read{,str}() have been around for ~5 years by now, there
are plenty of users at least on x86 still relying on them today, so we
cannot remove them entirely w/o breaking the BPF tracing ecosystem.
However, their use should be restricted to archs with non-overlapping
address ranges where they are working in their current form. Therefore,
move this behind a CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE and
have x86, arm64, arm select it (other archs supporting it can follow-up
on it as well).
For the remaining archs, they can workaround easily by relying on the
feature probe from bpftool which spills out defines that can be used out
of BPF C code to implement the drop-in replacement for old/new kernels
via: bpftool feature probe macro
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/bpf/20200515101118.6508-2-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b2a5212fb6 upstream.
Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the
very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on
archs with overlapping address ranges.
While the helpers have been addressed through work in 6ae08ae3de ("bpf: Add
probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need
an option for bpf_trace_printk() as well to fix it.
Similarly as with the helpers, force users to make an explicit choice by adding
%pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding
strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS.
The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended
for other objects aside strings that are probed and printed under tracing, and
reused out of other facilities like bpf_seq_printf() or BTF based type printing.
Existing behavior of %s for current users is still kept working for archs where it
is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
For archs not having this property we fall-back to pick probing under KERNEL_DS as
a sensible default.
Fixes: 8d3b7dce86 ("bpf: add support for %s specifier to bpf_trace_printk()")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e92888c72f upstream.
Currently, tracing/fentry and tracing/fexit prog
return values are not enforced. In trampoline codes,
the fentry/fexit prog return values are ignored.
Let us enforce it to be 0 to avoid confusion and
allows potential future extension.
This patch also explicitly added return value
checking for tracing/raw_tp, tracing/fmod_ret,
and freplace programs such that these program
return values can be anything. The purpose are
two folds:
1. to make it explicit about return value expectations
for these programs in verifier.
2. for tracing prog_type, if a future attach type
is added, the default is -ENOTSUPP which will
enforce to specify return value ranges explicitly.
Fixes: fec56f5890 ("bpf: Introduce BPF trampoline")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200514053206.1298415-1-yhs@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 78a5255ffb upstream.
We have some rather random rules about when we accept the
"maybe-initialized" warnings, and when we don't.
For example, we consider it unreliable for gcc versions < 4.9, but also
if -O3 is enabled, or if optimizing for size. And then various kernel
config options disabled it, because they know that they trigger that
warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES).
And now gcc-10 seems to be introducing a lot of those warnings too, so
it falls under the same heading as 4.9 did.
At the same time, we have a very straightforward way to _enable_ that
warning when wanted: use "W=2" to enable more warnings.
So stop playing these ad-hoc games, and just disable that warning by
default, with the known and straight-forward "if you want to work on the
extra compiler warnings, use W=123".
Would it be great to have code that is always so obvious that it never
confuses the compiler whether a variable is used initialized or not?
Yes, it would. In a perfect world, the compilers would be smarter, and
our source code would be simpler.
That's currently not the world we live in, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 333291ce50 ]
mmap() subsystem allows user-space application to memory-map region with
initial page offset. This wasn't taken into account in initial implementation
of BPF array memory-mapping. This would result in wrong pages, not taking into
account requested page shift, being memory-mmaped into user-space. This patch
fixes this gap and adds a test for such scenario.
Fixes: fc9702273e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200512235925.3817805-1-andriin@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 59566b0b62 ]
Booting one of my machines, it triggered the following crash:
Kernel/User page tables isolation: enabled
ftrace: allocating 36577 entries in 143 pages
Starting tracer 'function'
BUG: unable to handle page fault for address: ffffffffa000005c
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
PGD 2014067 P4D 2014067 PUD 2015063 PMD 7b253067 PTE 7b252061
Oops: 0003 [#1] PREEMPT SMP PTI
CPU: 0 PID: 0 Comm: swapper Not tainted 5.4.0-test+ #24
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
RIP: 0010:text_poke_early+0x4a/0x58
Code: 34 24 48 89 54 24 08 e8 bf 72 0b 00 48 8b 34 24 48 8b 4c 24 08 84 c0 74 0b 48 89 df f3 a4 48 83 c4 10 5b c3 9c 58 fa 48 89 df <f3> a4 50 9d 48 83 c4 10 5b e9 d6 f9 ff ff
0 41 57 49
RSP: 0000:ffffffff82003d38 EFLAGS: 00010046
RAX: 0000000000000046 RBX: ffffffffa000005c RCX: 0000000000000005
RDX: 0000000000000005 RSI: ffffffff825b9a90 RDI: ffffffffa000005c
RBP: ffffffffa000005c R08: 0000000000000000 R09: ffffffff8206e6e0
R10: ffff88807b01f4c0 R11: ffffffff8176c106 R12: ffffffff8206e6e0
R13: ffffffff824f2440 R14: 0000000000000000 R15: ffffffff8206eac0
FS: 0000000000000000(0000) GS:ffff88807d400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffa000005c CR3: 0000000002012000 CR4: 00000000000006b0
Call Trace:
text_poke_bp+0x27/0x64
? mutex_lock+0x36/0x5d
arch_ftrace_update_trampoline+0x287/0x2d5
? ftrace_replace_code+0x14b/0x160
? ftrace_update_ftrace_func+0x65/0x6c
__register_ftrace_function+0x6d/0x81
ftrace_startup+0x23/0xc1
register_ftrace_function+0x20/0x37
func_set_flag+0x59/0x77
__set_tracer_option.isra.19+0x20/0x3e
trace_set_options+0xd6/0x13e
apply_trace_boot_options+0x44/0x6d
register_tracer+0x19e/0x1ac
early_trace_init+0x21b/0x2c9
start_kernel+0x241/0x518
? load_ucode_intel_bsp+0x21/0x52
secondary_startup_64+0xa4/0xb0
I was able to trigger it on other machines, when I added to the kernel
command line of both "ftrace=function" and "trace_options=func_stack_trace".
The cause is the "ftrace=function" would register the function tracer
and create a trampoline, and it will set it as executable and
read-only. Then the "trace_options=func_stack_trace" would then update
the same trampoline to include the stack tracer version of the function
tracer. But since the trampoline already exists, it updates it with
text_poke_bp(). The problem is that text_poke_bp() called while
system_state == SYSTEM_BOOTING, it will simply do a memcpy() and not
the page mapping, as it would think that the text is still read-write.
But in this case it is not, and we take a fault and crash.
Instead, lets keep the ftrace trampolines read-write during boot up,
and then when the kernel executable text is set to read-only, the
ftrace trampolines get set to read-only as well.
Link: https://lkml.kernel.org/r/20200430202147.4dc6e2de@oasis.local.home
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: stable@vger.kernel.org
Fixes: 768ae4406a ("x86/ftrace: Use text_poke()")
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 8b1fac2e73 ]
A bug report was posted that running the preempt irq delay module on a slow
machine, and removing it quickly could lead to the thread created by the
modlue to execute after the module is removed, and this could cause the
kernel to crash. The fix for this was to call kthread_stop() after creating
the thread to make sure it finishes before allowing the module to be
removed.
Now this caused the opposite problem on fast machines. What now happens is
the kthread_stop() can cause the kthread never to execute and the test never
to run. To fix this, add a completion and wait for the kthread to execute,
then wait for it to end.
This issue caused the ftracetest selftests to fail on the preemptirq tests.
Link: https://lore.kernel.org/r/20200510114210.15d9e4af@oasis.local.home
Cc: stable@vger.kernel.org
Fixes: d16a8c3107 ("tracing: Wait for preempt irq delay thread to finish")
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 3f2c788a13 ]
Jan reported an issue where an interaction between sign-extending clone's
flag argument on ppc64le and the new CLONE_INTO_CGROUP feature causes
clone() to consistently fail with EBADF.
The whole story is a little longer. The legacy clone() syscall is odd in a
bunch of ways and here two things interact. First, legacy clone's flag
argument is word-size dependent, i.e. it's an unsigned long whereas most
system calls with flag arguments use int or unsigned int. Second, legacy
clone() ignores unknown and deprecated flags. The two of them taken
together means that users on 64bit systems can pass garbage for the upper
32bit of the clone() syscall since forever and things would just work fine.
Just try this on a 64bit kernel prior to v5.7-rc1 where this will succeed
and on v5.7-rc1 where this will fail with EBADF:
int main(int argc, char *argv[])
{
pid_t pid;
/* Note that legacy clone() has different argument ordering on
* different architectures so this won't work everywhere.
*
* Only set the upper 32 bits.
*/
pid = syscall(__NR_clone, 0xffffffff00000000 | SIGCHLD,
NULL, NULL, NULL, NULL);
if (pid < 0)
exit(EXIT_FAILURE);
if (pid == 0)
exit(EXIT_SUCCESS);
if (wait(NULL) != pid)
exit(EXIT_FAILURE);
exit(EXIT_SUCCESS);
}
Since legacy clone() couldn't be extended this was not a problem so far and
nobody really noticed or cared since nothing in the kernel ever bothered to
look at the upper 32 bits.
But once we introduced clone3() and expanded the flag argument in struct
clone_args to 64 bit we opened this can of worms. With the first flag-based
extension to clone3() making use of the upper 32 bits of the flag argument
we've effectively made it possible for the legacy clone() syscall to reach
clone3() only flags. The sign extension scenario is just the odd
corner-case that we needed to figure this out.
The reason we just realized this now and not already when we introduced
CLONE_CLEAR_SIGHAND was that CLONE_INTO_CGROUP assumes that a valid cgroup
file descriptor has been given. So the sign extension (or the user
accidently passing garbage for the upper 32 bits) caused the
CLONE_INTO_CGROUP bit to be raised and the kernel to error out when it
didn't find a valid cgroup file descriptor.
Let's fix this by always capping the upper 32 bits for all codepaths that
are not aware of clone3() features. This ensures that we can't reach
clone3() only features by accident via legacy clone as with the sign
extension case and also that legacy clone() works exactly like before, i.e.
ignoring any unknown flags. This solution risks no regressions and is also
pretty clean.
Fixes: 7f192e3cd3 ("fork: add clone3")
Fixes: ef2c41cf38 ("clone3: allow spawning processes into cgroups")
Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Cc: Florian Weimer <fw@deneb.enyo.de>
Cc: libc-alpha@sourceware.org
Cc: stable@vger.kernel.org # 5.3+
Link: https://sourceware.org/pipermail/libc-alpha/2020-May/113596.html
Link: https://lore.kernel.org/r/20200507103214.77218-1-christian.brauner@ubuntu.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit db803036ad ]
If a UMH process created by fork_usermode_blob() fails to execute,
a pair of struct file allocated by umh_pipe_setup() will leak.
Under normal conditions, the caller (like bpfilter) needs to manage the
lifetime of the UMH and its two pipes. But when fork_usermode_blob()
fails, the caller doesn't really have a way to know what needs to be
done. It seems better to do the cleanup ourselves in this case.
Fixes: 449325b52b ("umh: introduce fork_usermode_blob() helper")
Signed-off-by: Vincent Minet <v.minet@criteo.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 11f5efc3ab upstream.
x86_64 lazily maps in the vmalloc pages, and the way this works with per_cpu
areas can be complex, to say the least. Mappings may happen at boot up, and
if nothing synchronizes the page tables, those page mappings may not be
synced till they are used. This causes issues for anything that might touch
one of those mappings in the path of the page fault handler. When one of
those unmapped mappings is touched in the page fault handler, it will cause
another page fault, which in turn will cause a page fault, and leave us in
a loop of page faults.
Commit 763802b53a ("x86/mm: split vmalloc_sync_all()") split
vmalloc_sync_all() into vmalloc_sync_unmappings() and
vmalloc_sync_mappings(), as on system exit, it did not need to do a full
sync on x86_64 (although it still needed to be done on x86_32). By chance,
the vmalloc_sync_all() would synchronize the page mappings done at boot up
and prevent the per cpu area from being a problem for tracing in the page
fault handler. But when that synchronization in the exit of a task became a
nop, it caused the problem to appear.
Link: https://lore.kernel.org/r/20200429054857.66e8e333@oasis.local.home
Cc: stable@vger.kernel.org
Fixes: 737223fbca ("tracing: Consolidate buffer allocation code")
Reported-by: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
Suggested-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d16a8c3107 upstream.
Running on a slower machine, it is possible that the preempt delay kernel
thread may still be executing if the module was immediately removed after
added, and this can cause the kernel to crash as the kernel thread might be
executing after its code has been removed.
There's no reason that the caller of the code shouldn't just wait for the
delay thread to finish, as the thread can also be created by a trigger in
the sysfs code, which also has the same issues.
Link: http://lore.kernel.org/r/5EA2B0C8.2080706@cn.fujitsu.com
Cc: stable@vger.kernel.org
Fixes: 793937236d ("lib: Add module for testing preemptoff/irqsoff latency tracers")
Reported-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit da0f1f4167 upstream.
Fix boottime kprobe events to use API correctly for
multiple events.
For example, when we set a multiprobe kprobe events in
bootconfig like below,
ftrace.event.kprobes.myevent {
probes = "vfs_read $arg1 $arg2", "vfs_write $arg1 $arg2"
}
This cause an error;
trace_boot: Failed to add probe: p:kprobes/myevent (null) vfs_read $arg1 $arg2 vfs_write $arg1 $arg2
This shows the 1st argument becomes NULL and multiprobes
are merged to 1 probe.
Link: http://lkml.kernel.org/r/158779375766.6082.201939936008972838.stgit@devnote2
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 29a1548105 ("tracing: Change trace_boot to use kprobe_event interface")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 2351f8d295 upstream.
Currently the kernel threads are not frozen in software_resume(), so
between dpm_suspend_start(PMSG_QUIESCE) and resume_target_kernel(),
system_freezable_power_efficient_wq can still try to submit SCSI
commands and this can cause a panic since the low level SCSI driver
(e.g. hv_storvsc) has quiesced the SCSI adapter and can not accept
any SCSI commands: https://lkml.org/lkml/2020/4/10/47
At first I posted a fix (https://lkml.org/lkml/2020/4/21/1318) trying
to resolve the issue from hv_storvsc, but with the help of
Bart Van Assche, I realized it's better to fix software_resume(),
since this looks like a generic issue, not only pertaining to SCSI.
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit e0d648f9d8 ]
Work around this warning:
kernel/sched/cputime.c: In function ‘kcpustat_field’:
kernel/sched/cputime.c:1007:6: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
because GCC can't see that val is used only when err is 0.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200327214334.GF8015@zn.tnic
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 3662daf023 ]
The "isolcpus=" parameter allows sub-parameters before the cpulist is
specified, and if the parser detects an unknown sub-parameters the whole
parameter will be ignored.
This design is incompatible with itself when new sub-parameters are added.
An older kernel will not recognize the new sub-parameter and will
invalidate the whole parameter so the CPU isolation will not take
effect. It emits a warning:
isolcpus: Error, unknown flag
The better and compatible way is to allow "isolcpus=" to skip unknown
sub-parameters, so that even if new sub-parameters are added an older
kernel will still be able to behave as usual even if with the new
sub-parameter specified on the command line.
Ideally this should have been there when the first sub-parameter for
"isolcpus=" was introduced.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200403223517.406353-1-peterx@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 03f87c0b45 upstream.
For some program types, the verifier relies on the expected_attach_type of
the program being verified in the verification process. However, for
freplace programs, the attach type was not propagated along with the
verifier ops, so the expected_attach_type would always be zero for freplace
programs.
This in turn caused the verifier to sometimes make the wrong call for
freplace programs. For all existing uses of expected_attach_type for this
purpose, the result of this was only false negatives (i.e., freplace
functions would be rejected by the verifier even though they were valid
programs for the target they were replacing). However, should a false
positive be introduced, this can lead to out-of-bounds accesses and/or
crashes.
The fix introduced in this patch is to propagate the expected_attach_type
to the freplace program during verification, and reset it after that is
done.
Fixes: be8704ff07 ("bpf: Introduce dynamic program extensions")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158773526726.293902.13257293296560360508.stgit@toke.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8ff3571f7e upstream.
check_xadd() can cause check_ptr_to_btf_access() to be executed with
atype==BPF_READ and value_regno==-1 (meaning "just check whether the access
is okay, don't tell me what type it will result in").
Handle that case properly and skip writing type information, instead of
indexing into the registers at index -1 and writing into out-of-bounds
memory.
Note that at least at the moment, you can't actually write through a BTF
pointer, so check_xadd() will reject the program after calling
check_ptr_to_btf_access with atype==BPF_WRITE; but that's after the
verifier has already corrupted memory.
This patch assumes that BTF pointers are not available in unprivileged
programs.
Fixes: 9e15db6613 ("bpf: Implement accurate raw_tp context access via BTF")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200417000007.10734-2-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit eaf5a92ebd upstream.
uclamp_fork() resets the uclamp values to their default when the
reset-on-fork flag is set. It also checks whether the task has a RT
policy, and sets its uclamp.min to 1024 accordingly. However, during
reset-on-fork, the task's policy is lowered to SCHED_NORMAL right after,
hence leading to an erroneous uclamp.min setting for the new task if it
was forked from RT.
Fix this by removing the unnecessary check on rt_task() in
uclamp_fork() as this doesn't make sense if the reset-on-fork flag is
set.
Fixes: 1a00d99997 ("sched/uclamp: Set default clamps for RT tasks")
Reported-by: Chitti Babu Theegala <ctheegal@codeaurora.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Patrick Bellasi <patrick.bellasi@matbug.net>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/20200416085956.217587-1-qperret@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit bc23d0e3f7 upstream.
When the kernel is built with CONFIG_DEBUG_PER_CPU_MAPS, the cpumap code
can trigger a spurious warning if CONFIG_CPUMASK_OFFSTACK is also set. This
happens because in this configuration, NR_CPUS can be larger than
nr_cpumask_bits, so the initial check in cpu_map_alloc() is not sufficient
to guard against hitting the warning in cpumask_check().
Fix this by explicitly checking the supplied key against the
nr_cpumask_bits variable before calling cpu_possible().
Fixes: 6710e11269 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Xiumei Mu <xmu@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200416083120.453718-1-toke@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6e7e63cbb0 upstream.
When check_xadd() verifies an XADD operation on a pointer to a stack slot
containing a spilled pointer, check_stack_read() verifies that the read,
which is part of XADD, is valid. However, since the placeholder value -1 is
passed as `value_regno`, check_stack_read() can only return a binary
decision and can't return the type of the value that was read. The intent
here is to verify whether the value read from the stack slot may be used as
a SCALAR_VALUE; but since check_stack_read() doesn't check the type, and
the type information is lost when check_stack_read() returns, this is not
enforced, and a malicious user can abuse XADD to leak spilled kernel
pointers.
Fix it by letting check_stack_read() verify that the value is usable as a
SCALAR_VALUE if no type information is passed to the caller.
To be able to use __is_pointer_value() in check_stack_read(), move it up.
Fix up the expected unprivileged error message for a BPF selftest that,
until now, assumed that unprivileged users can use XADD on stack-spilled
pointers. This also gives us a test for the behavior introduced in this
patch for free.
In theory, this could also be fixed by forbidding XADD on stack spills
entirely, since XADD is a locked operation (for operations on memory with
concurrency) and there can't be any concurrency on the BPF stack; but
Alexei has said that he wants to keep XADD on stack slots working to avoid
changes to the test suite [1].
The following BPF program demonstrates how to leak a BPF map pointer as an
unprivileged user using this bug:
// r7 = map_pointer
BPF_LD_MAP_FD(BPF_REG_7, small_map),
// r8 = launder(map_pointer)
BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_7, -8),
BPF_MOV64_IMM(BPF_REG_1, 0),
((struct bpf_insn) {
.code = BPF_STX | BPF_DW | BPF_XADD,
.dst_reg = BPF_REG_FP,
.src_reg = BPF_REG_1,
.off = -8
}),
BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_FP, -8),
// store r8 into map
BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_7),
BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -4),
BPF_ST_MEM(BPF_W, BPF_REG_ARG2, 0, 0),
BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
BPF_EXIT_INSN(),
BPF_STX_MEM(BPF_DW, BPF_REG_0, BPF_REG_8, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN()
[1] https://lore.kernel.org/bpf/20200416211116.qxqcza5vo2ddnkdq@ast-mbp.dhcp.thefacebook.com/
Fixes: 17a5267067 ("bpf: verifier (add verifier core)")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200417000007.10734-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ab6f762f0f upstream.
printk_deferred(), similarly to printk_safe/printk_nmi, does not
immediately attempt to print a new message on the consoles, avoiding
calls into non-reentrant kernel paths, e.g. scheduler or timekeeping,
which potentially can deadlock the system.
Those printk() flavors, instead, rely on per-CPU flush irq_work to print
messages from safer contexts. For same reasons (recursive scheduler or
timekeeping calls) printk() uses per-CPU irq_work in order to wake up
user space syslog/kmsg readers.
However, only printk_safe/printk_nmi do make sure that per-CPU areas
have been initialised and that it's safe to modify per-CPU irq_work.
This means that, for instance, should printk_deferred() be invoked "too
early", that is before per-CPU areas are initialised, printk_deferred()
will perform illegal per-CPU access.
Lech Perczak [0] reports that after commit 1b710b1b10 ("char/random:
silence a lockdep splat with printk()") user-space syslog/kmsg readers
are not able to read new kernel messages.
The reason is printk_deferred() being called too early (as was pointed
out by Petr and John).
Fix printk_deferred() and do not queue per-CPU irq_work before per-CPU
areas are initialized.
Link: https://lore.kernel.org/lkml/aa0732c6-5c4e-8a8b-a1c1-75ebe3dca05b@camlintechnologies.com/
Reported-by: Lech Perczak <l.perczak@camlintechnologies.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: Jann Horn <jannh@google.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 763dafc520 upstream.
Commit 7561252892 ("audit: always check the netlink payload length
in audit_receive_msg()") fixed a number of missing message length
checks, but forgot to check the length of userspace generated audit
records. The good news is that you need CAP_AUDIT_WRITE to submit
userspace audit records, which is generally only given to trusted
processes, so the impact should be limited.
Cc: stable@vger.kernel.org
Fixes: 7561252892 ("audit: always check the netlink payload length in audit_receive_msg()")
Reported-by: syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 61e713bdca upstream.
Christof Meerwald <cmeerw@cmeerw.org> writes:
> Hi,
>
> this is probably related to commit
> 7a0cf09494 (signal: Correct namespace
> fixups of si_pid and si_uid).
>
> With a 5.6.5 kernel I am seeing SIGCHLD signals that don't include a
> properly set si_pid field - this seems to happen for multi-threaded
> child processes.
>
> A simple test program (based on the sample from the signalfd man page):
>
> #include <sys/signalfd.h>
> #include <signal.h>
> #include <unistd.h>
> #include <spawn.h>
> #include <stdlib.h>
> #include <stdio.h>
>
> #define handle_error(msg) \
> do { perror(msg); exit(EXIT_FAILURE); } while (0)
>
> int main(int argc, char *argv[])
> {
> sigset_t mask;
> int sfd;
> struct signalfd_siginfo fdsi;
> ssize_t s;
>
> sigemptyset(&mask);
> sigaddset(&mask, SIGCHLD);
>
> if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1)
> handle_error("sigprocmask");
>
> pid_t chldpid;
> char *chldargv[] = { "./sfdclient", NULL };
> posix_spawn(&chldpid, "./sfdclient", NULL, NULL, chldargv, NULL);
>
> sfd = signalfd(-1, &mask, 0);
> if (sfd == -1)
> handle_error("signalfd");
>
> for (;;) {
> s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo));
> if (s != sizeof(struct signalfd_siginfo))
> handle_error("read");
>
> if (fdsi.ssi_signo == SIGCHLD) {
> printf("Got SIGCHLD %d %d %d %d\n",
> fdsi.ssi_status, fdsi.ssi_code,
> fdsi.ssi_uid, fdsi.ssi_pid);
> return 0;
> } else {
> printf("Read unexpected signal\n");
> }
> }
> }
>
>
> and a multi-threaded client to test with:
>
> #include <unistd.h>
> #include <pthread.h>
>
> void *f(void *arg)
> {
> sleep(100);
> }
>
> int main()
> {
> pthread_t t[8];
>
> for (int i = 0; i != 8; ++i)
> {
> pthread_create(&t[i], NULL, f, NULL);
> }
> }
>
> I tried to do a bit of debugging and what seems to be happening is
> that
>
> /* From an ancestor pid namespace? */
> if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
>
> fails inside task_pid_nr_ns because the check for "pid_alive" fails.
>
> This code seems to be called from do_notify_parent and there we
> actually have "tsk != current" (I am assuming both are threads of the
> current process?)
I instrumented the code with a warning and received the following backtrace:
> WARNING: CPU: 0 PID: 777 at kernel/pid.c:501 __task_pid_nr_ns.cold.6+0xc/0x15
> Modules linked in:
> CPU: 0 PID: 777 Comm: sfdclient Not tainted 5.7.0-rc1userns+ #2924
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> RIP: 0010:__task_pid_nr_ns.cold.6+0xc/0x15
> Code: ff 66 90 48 83 ec 08 89 7c 24 04 48 8d 7e 08 48 8d 74 24 04 e8 9a b6 44 00 48 83 c4 08 c3 48 c7 c7 59 9f ac 82 e8 c2 c4 04 00 <0f> 0b e9 3fd
> RSP: 0018:ffffc9000042fbf8 EFLAGS: 00010046
> RAX: 000000000000000c RBX: 0000000000000000 RCX: ffffc9000042faf4
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff81193d29
> RBP: ffffc9000042fc18 R08: 0000000000000000 R09: 0000000000000001
> R10: 000000100f938416 R11: 0000000000000309 R12: ffff8880b941c140
> R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880b941c140
> FS: 0000000000000000(0000) GS:ffff8880bca00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f2e8c0a32e0 CR3: 0000000002e10000 CR4: 00000000000006f0
> Call Trace:
> send_signal+0x1c8/0x310
> do_notify_parent+0x50f/0x550
> release_task.part.21+0x4fd/0x620
> do_exit+0x6f6/0xaf0
> do_group_exit+0x42/0xb0
> get_signal+0x13b/0xbb0
> do_signal+0x2b/0x670
> ? __audit_syscall_exit+0x24d/0x2b0
> ? rcu_read_lock_sched_held+0x4d/0x60
> ? kfree+0x24c/0x2b0
> do_syscall_64+0x176/0x640
> ? trace_hardirqs_off_thunk+0x1a/0x1c
> entry_SYSCALL_64_after_hwframe+0x49/0xb3
The immediate problem is as Christof noticed that "pid_alive(current) == false".
This happens because do_notify_parent is called from the last thread to exit
in a process after that thread has been reaped.
The bigger issue is that do_notify_parent can be called from any
process that manages to wait on a thread of a multi-threaded process
from wait_task_zombie. So any logic based upon current for
do_notify_parent is just nonsense, as current can be pretty much
anything.
So change do_notify_parent to call __send_signal directly.
Inspecting the code it appears this problem has existed since the pid
namespace support started handling this case in 2.6.30. This fix only
backports to 7a0cf09494 ("signal: Correct namespace fixups of si_pid and si_uid")
where the problem logic was moved out of __send_signal and into send_signal.
Cc: stable@vger.kernel.org
Fixes: 6588c1e3ff ("signals: SI_USER: Masquerade si_pid when crossing pid ns boundary")
Ref: 921cf9f630 ("signals: protect cinit from unblocked SIG_DFL signals")
Link: https://lore.kernel.org/lkml/20200419201336.GI22017@edge.cmeerw.net/
Reported-by: Christof Meerwald <cmeerw@cmeerw.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d3296fb372 ]
We hit following warning when running tests on kernel
compiled with CONFIG_DEBUG_ATOMIC_SLEEP=y:
WARNING: CPU: 19 PID: 4472 at mm/gup.c:2381 __get_user_pages_fast+0x1a4/0x200
CPU: 19 PID: 4472 Comm: dummy Not tainted 5.6.0-rc6+ #3
RIP: 0010:__get_user_pages_fast+0x1a4/0x200
...
Call Trace:
perf_prepare_sample+0xff1/0x1d90
perf_event_output_forward+0xe8/0x210
__perf_event_overflow+0x11a/0x310
__intel_pmu_pebs_event+0x657/0x850
intel_pmu_drain_pebs_nhm+0x7de/0x11d0
handle_pmi_common+0x1b2/0x650
intel_pmu_handle_irq+0x17b/0x370
perf_event_nmi_handler+0x40/0x60
nmi_handle+0x192/0x590
default_do_nmi+0x6d/0x150
do_nmi+0x2f9/0x3c0
nmi+0x8e/0xd7
While __get_user_pages_fast() is IRQ-safe, it calls access_ok(),
which warns on:
WARN_ON_ONCE(!in_task() && !pagefault_disabled())
Peter suggested disabling page faults around __get_user_pages_fast(),
which gets rid of the warning in access_ok() call.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200407141427.3184722-1-jolsa@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit cdcda0d1f8 ]
The upper 32-bit physical address gets truncated inadvertently
when dma_direct_get_required_mask() invokes phys_to_dma_direct().
This results in dma_addressing_limited() return incorrect value
when used in platforms with LPAE enabled.
Fix it here by explicitly type casting 'max_pfn' to phys_addr_t
in order to prevent overflow of intermediate value while evaluating
'(max_pfn - 1) << PAGE_SHIFT'.
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ no upstream commit ]
See the glory details in 100605035e ("bpf: Verifier, do_refine_retval_range
may clamp umin to 0 incorrectly") for why 849fa50662 ("bpf/verifier: refine
retval R0 state for bpf_get_stack helper") is buggy. The whole series however
is not suitable for stable since it adds significant amount [0] of verifier
complexity in order to add 32bit subreg tracking. Something simpler is needed.
Unfortunately, reverting 849fa50662 ("bpf/verifier: refine retval R0 state
for bpf_get_stack helper") or just cherry-picking 100605035e ("bpf: Verifier,
do_refine_retval_range may clamp umin to 0 incorrectly") is not an option since
it will break existing tracing programs badly (at least those that are using
bpf_get_stack() and bpf_probe_read_str() helpers). Not fixing it in stable is
also not an option since on 4.19 kernels an error will cause a soft-lockup due
to hitting dead-code sanitized branch since we don't hard-wire such branches
in old kernels yet. But even then for 5.x 849fa50662 ("bpf/verifier: refine
retval R0 state for bpf_get_stack helper") would cause wrong bounds on the
verifier simluation when an error is hit.
In one of the earlier iterations of mentioned patch series for upstream there
was the concern that just using smax_value in do_refine_retval_range() would
nuke bounds by subsequent <<32 >>32 shifts before the comparison against 0 [1]
which eventually led to the 32bit subreg tracking in the first place. While I
initially went for implementing the idea [1] to pattern match the two shift
operations, it turned out to be more complex than actually needed, meaning, we
could simply treat do_refine_retval_range() similarly to how we branch off
verification for conditionals or under speculation, that is, pushing a new
reg state to the stack for later verification. This means, instead of verifying
the current path with the ret_reg in [S32MIN, msize_max_value] interval where
later bounds would get nuked, we split this into two: i) for the success case
where ret_reg can be in [0, msize_max_value], and ii) for the error case with
ret_reg known to be in interval [S32MIN, -1]. Latter will preserve the bounds
during these shift patterns and can match reg < 0 test. test_progs also succeed
with this approach.
[0] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/
[1] https://lore.kernel.org/bpf/158015334199.28573.4940395881683556537.stgit@john-XPS-13-9370/T/#m2e0ad1d5949131014748b6daa48a3495e7f0456d
Fixes: 849fa50662 ("bpf/verifier: refine retval R0 state for bpf_get_stack helper")
Reported-by: Lorenzo Fontana <fontanalorenz@gmail.com>
Reported-by: Leonardo Di Donato <leodidonato@gmail.com>
Reported-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 80c503e0e6 upstream.
The __torture_print_stats() function in locktorture.c carefully
initializes local variable "min" to statp[0].n_lock_acquired, but
then compares it to statp[i].n_lock_fail. Given that the .n_lock_fail
field should normally be zero, and given the initialization, it seems
reasonable to display the maximum and minimum number acquisitions
instead of miscomputing the maximum and minimum number of failures.
This commit therefore switches from failures to acquisitions.
And this turns out to be not only a day-zero bug, but entirely my
own fault. I hate it when that happens!
Fixes: 0af3fe1efa ("locktorture: Add a lock-torture kernel module")
Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 286c21de32 ]
pageno is an int and the PAGE_SHIFT shift is done on an int,
overflowing if the memory is bigger than 2G
This can be reproduced using for example a reserved-memory of 4G
reserved-memory {
#address-cells = <2>;
#size-cells = <2>;
ranges;
reserved_dma: buffer@0 {
compatible = "shared-dma-pool";
no-map;
reg = <0x5 0x00000000 0x1 0x0>;
};
};
Signed-off-by: Kevin Grandemange <kevin.grandemange@allegrodvt.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 1f6cb19be2 upstream.
VM_MAYWRITE flag during initial memory mapping determines if already mmap()'ed
pages can be later remapped as writable ones through mprotect() call. To
prevent user application to rewrite contents of memory-mapped as read-only and
subsequently frozen BPF map, remove VM_MAYWRITE flag completely on initially
read-only mapping.
Alternatively, we could treat any memory-mapping on unfrozen map as writable
and bump writecnt instead. But there is little legitimate reason to map
BPF map as read-only and then re-mmap() it as writable through mprotect(),
instead of just mmap()'ing it as read/write from the very beginning.
Also, at the suggestion of Jann Horn, drop unnecessary refcounting in mmap
operations. We can just rely on VMA holding reference to BPF map's file
properly.
Fixes: fc9702273e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/bpf/20200410202613.3679837-1-andriin@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 94d440d618 upstream.
Michael Kerrisk suggested to replace numeric clock IDs with symbolic names.
Now the content of these files looks like this:
$ cat /proc/774/timens_offsets
monotonic 864000 0
boottime 1728000 0
For setting offsets, both representations of clocks (numeric and symbolic)
can be used.
As for compatibility, it is acceptable to change things as long as
userspace doesn't care. The format of timens_offsets files is very new and
there are no userspace tools yet which rely on this format.
But three projects crun, util-linux and criu rely on the interface of
setting time offsets and this is why it's required to continue supporting
the numeric clock IDs on write.
Fixes: 04a8682a71 ("fs/proc: Introduce /proc/pid/timens_offsets")
Suggested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200411154031.642557-1-avagin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit bf37da98c5 upstream.
The rcu_nmi_enter_common() function can be invoked both in interrupt
and NMI handlers. If it is invoked from process context (as opposed
to userspace or idle context) on a nohz_full CPU, it might acquire the
CPU's leaf rcu_node structure's ->lock. Because this lock is held only
with interrupts disabled, this is safe from an interrupt handler, but
doing so from an NMI handler can result in self-deadlock.
This commit therefore adds "irq" to the "if" condition so as to only
acquire the ->lock from irq handlers or process context, never from
an NMI handler.
Fixes: 5b14557b07 ("rcu: Avoid tick_dep_set_cpu() misordering")
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: <stable@vger.kernel.org> # 5.5.x
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 604dca5e3a ]
The BPF verifier tried to track values based on 32-bit comparisons by
(ab)using the tnum state via 581738a681 ("bpf: Provide better register
bounds after jmp32 instructions"). The idea is that after a check like
this:
if ((u32)r0 > 3)
exit
We can't meaningfully constrain the arithmetic-range-based tracking, but
we can update the tnum state to (value=0,mask=0xffff'ffff'0000'0003).
However, the implementation from 581738a681 didn't compute the tnum
constraint based on the fixed operand, but instead derives it from the
arithmetic-range-based tracking. This means that after the following
sequence of operations:
if (r0 >= 0x1'0000'0001)
exit
if ((u32)r0 > 7)
exit
The verifier assumed that the lower half of r0 is in the range (0, 0)
and apply the tnum constraint (value=0,mask=0xffff'ffff'0000'0000) thus
causing the overall tnum to be (value=0,mask=0x1'0000'0000), which was
incorrect. Provide a fixed implementation.
Fixes: 581738a681 ("bpf: Provide better register bounds after jmp32 instructions")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200330160324.15259-3-daniel@iogearbox.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 2c2366c754 ]
We can deduce the ctx and cpuctx from the event, no need to pass them
along. Remove the structure and pass in can_add_hw directly.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 33238c5045 ]
Song reports that installing cgroup events is broken since:
db0503e4f6 ("perf/core: Optimize perf_install_in_event()")
The problem being that cgroup events try to track cpuctx->cgrp even
for disabled events, which is pointless and actively harmful since the
above commit. Rework the code to have explicit enable/disable hooks
for cgroup events, such that we can limit cgroup tracking to active
events.
More specifically, since the above commit disabled events are no
longer added to their context from the 'right' CPU, and we can't
access things like the current cgroup for a remote CPU.
Cc: <stable@vger.kernel.org> # v5.5+
Fixes: db0503e4f6 ("perf/core: Optimize perf_install_in_event()")
Reported-by: Song Liu <songliubraving@fb.com>
Tested-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200318193337.GB20760@hirez.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit d7d27cfc5c upstream.
Patch series "module autoloading fixes and cleanups", v5.
This series fixes a bug where request_module() was reporting success to
kernel code when module autoloading had been completely disabled via
'echo > /proc/sys/kernel/modprobe'.
It also addresses the issues raised on the original thread
(https://lkml.kernel.org/lkml/20200310223731.126894-1-ebiggers@kernel.org/T/#u)
bydocumenting the modprobe sysctl, adding a self-test for the empty path
case, and downgrading a user-reachable WARN_ONCE().
This patch (of 4):
It's long been possible to disable kernel module autoloading completely
(while still allowing manual module insertion) by setting
/proc/sys/kernel/modprobe to the empty string.
This can be preferable to setting it to a nonexistent file since it
avoids the overhead of an attempted execve(), avoids potential
deadlocks, and avoids the call to security_kernel_module_request() and
thus on SELinux-based systems eliminates the need to write SELinux rules
to dontaudit module_request.
However, when module autoloading is disabled in this way,
request_module() returns 0. This is broken because callers expect 0 to
mean that the module was successfully loaded.
Apparently this was never noticed because this method of disabling
module autoloading isn't used much, and also most callers don't use the
return value of request_module() since it's always necessary to check
whether the module registered its functionality or not anyway.
But improperly returning 0 can indeed confuse a few callers, for example
get_fs_type() in fs/filesystems.c where it causes a WARNING to be hit:
if (!fs && (request_module("fs-%.*s", len, name) == 0)) {
fs = __get_fs_type(name, len);
WARN_ONCE(!fs, "request_module fs-%.*s succeeded, but still no fs?\n", len, name);
}
This is easily reproduced with:
echo > /proc/sys/kernel/modprobe
mount -t NONEXISTENT none /
It causes:
request_module fs-NONEXISTENT succeeded, but still no fs?
WARNING: CPU: 1 PID: 1106 at fs/filesystems.c:275 get_fs_type+0xd6/0xf0
[...]
This should actually use pr_warn_once() rather than WARN_ONCE(), since
it's also user-reachable if userspace immediately unloads the module.
Regardless, request_module() should correctly return an error when it
fails. So let's make it return -ENOENT, which matches the error when
the modprobe binary doesn't exist.
I've also sent patches to document and test this case.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Ben Hutchings <benh@debian.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200310223731.126894-1-ebiggers@kernel.org
Link: http://lkml.kernel.org/r/20200312202552.241885-1-ebiggers@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
