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mm/mempolicy.c: fix error handling in set_mempolicy and mbind.

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commit cf01fb9985 upstream.

In the case that compat_get_bitmap fails we do not want to copy the
bitmap to the user as it will contain uninitialized stack data and leak
sensitive data.

Signed-off-by: Chris Salls <salls@cs.ucsb.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chris Salls
2017-04-07 23:48:11 -07:00
committed by Greg Kroah-Hartman
parent 24317cb6b4
commit cddab768d1
1 changed files with 8 additions and 12 deletions
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20
mm/mempolicy.c
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@@ -1524,7 +1524,6 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask, COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
compat_ulong_t, maxnode) compat_ulong_t, maxnode)
{ {
long err = 0;
unsigned long __user *nm = NULL; unsigned long __user *nm = NULL;
unsigned long nr_bits, alloc_size; unsigned long nr_bits, alloc_size;
DECLARE_BITMAP(bm, MAX_NUMNODES); DECLARE_BITMAP(bm, MAX_NUMNODES);
@@ -1533,14 +1532,13 @@ COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8; alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
if (nmask) { if (nmask) {
err = compat_get_bitmap(bm, nmask, nr_bits); if (compat_get_bitmap(bm, nmask, nr_bits))
return -EFAULT;
nm = compat_alloc_user_space(alloc_size); nm = compat_alloc_user_space(alloc_size);
err |= copy_to_user(nm, bm, alloc_size); if (copy_to_user(nm, bm, alloc_size))
return -EFAULT;
} }
if (err)
return -EFAULT;
return sys_set_mempolicy(mode, nm, nr_bits+1); return sys_set_mempolicy(mode, nm, nr_bits+1);
} }
@@ -1548,7 +1546,6 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
compat_ulong_t, mode, compat_ulong_t __user *, nmask, compat_ulong_t, mode, compat_ulong_t __user *, nmask,
compat_ulong_t, maxnode, compat_ulong_t, flags) compat_ulong_t, maxnode, compat_ulong_t, flags)
{ {
long err = 0;
unsigned long __user *nm = NULL; unsigned long __user *nm = NULL;
unsigned long nr_bits, alloc_size; unsigned long nr_bits, alloc_size;
nodemask_t bm; nodemask_t bm;
@@ -1557,14 +1554,13 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8; alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8;
if (nmask) { if (nmask) {
err = compat_get_bitmap(nodes_addr(bm), nmask, nr_bits); if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits))
return -EFAULT;
nm = compat_alloc_user_space(alloc_size); nm = compat_alloc_user_space(alloc_size);
err |= copy_to_user(nm, nodes_addr(bm), alloc_size); if (copy_to_user(nm, nodes_addr(bm), alloc_size))
return -EFAULT;
} }
if (err)
return -EFAULT;
return sys_mbind(start, len, mode, nm, nr_bits+1, flags); return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
} }