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commit0803278b0bupstream. Syzkaller hit 'KASAN: use-after-free Write in sanitize_ptr_alu' bug. Call trace: dump_stack+0xbf/0x12e print_address_description+0x6a/0x280 kasan_report+0x237/0x360 sanitize_ptr_alu+0x85a/0x8d0 adjust_ptr_min_max_vals+0x8f2/0x1ca0 adjust_reg_min_max_vals+0x8ed/0x22e0 do_check+0x1ca6/0x5d00 bpf_check+0x9ca/0x2570 bpf_prog_load+0xc91/0x1030 __se_sys_bpf+0x61e/0x1f00 do_syscall_64+0xc8/0x550 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fault injection trace: kfree+0xea/0x290 free_func_state+0x4a/0x60 free_verifier_state+0x61/0xe0 push_stack+0x216/0x2f0 <- inject failslab sanitize_ptr_alu+0x2b1/0x8d0 adjust_ptr_min_max_vals+0x8f2/0x1ca0 adjust_reg_min_max_vals+0x8ed/0x22e0 do_check+0x1ca6/0x5d00 bpf_check+0x9ca/0x2570 bpf_prog_load+0xc91/0x1030 __se_sys_bpf+0x61e/0x1f00 do_syscall_64+0xc8/0x550 entry_SYSCALL_64_after_hwframe+0x49/0xbe When kzalloc() fails in push_stack(), free_verifier_state() will free current verifier state. As push_stack() returns, dst_reg was restored if ptr_is_dst_reg is false. However, as member of the cur_state, dst_reg is also freed, and error occurs when dereferencing dst_reg. Simply fix it by testing ret of push_stack() before restoring dst_reg. Fixes:979d63d50c("bpf: prevent out of bounds speculation on pointer arithmetic") Signed-off-by: Xu Yu <xuyu@linux.alibaba.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.