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| author | Dmitry Vyukov <dvyukov@google.com> | 2016-02-04 15:27:50 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-02-05 07:41:52 (GMT) |
| commit | 75edb54a1dea5ea1c8d3d82e27dc9ee3070f5935 (patch) | |
| tree | b506284295fa3cd5bd6d99884f2dd8af4dadd323 | |
| parent | b37a05c083c85c2657dca9bbe1f5d79dccf756d5 (diff) | |
| download | linux-75edb54a1dea5ea1c8d3d82e27dc9ee3070f5935.tar.xz | |
x86: Fix KASAN false positives in thread_saved_pc()
thread_saved_pc() reads stack of a potentially running task.
This can cause false KASAN stack-out-of-bounds reports,
because the running task concurrently poisons and unpoisons
own stack.
The same happens in get_wchan(), and get get_wchan() was fixed
by using READ_ONCE_NOCHECK(). Do the same here.
Example KASAN report triggered by sysrq-t:
BUG: KASAN: out-of-bounds in sched_show_task+0x306/0x3b0 at addr ffff880043c97c18
Read of size 8 by task syz-executor/23839
[...]
page dumped because: kasan: bad access detected
[...]
Call Trace:
[<ffffffff8175ea0e>] __asan_report_load8_noabort+0x3e/0x40
[<ffffffff813e7a26>] sched_show_task+0x306/0x3b0
[<ffffffff813e7bf4>] show_state_filter+0x124/0x1a0
[<ffffffff82d2ca00>] fn_show_state+0x10/0x20
[<ffffffff82d2cf98>] k_spec+0xa8/0xe0
[<ffffffff82d3354f>] kbd_event+0xb9f/0x4000
[<ffffffff843ca8a7>] input_to_handler+0x3a7/0x4b0
[<ffffffff843d1954>] input_pass_values.part.5+0x554/0x6b0
[<ffffffff843d29bc>] input_handle_event+0x2ac/0x1070
[<ffffffff843d3a47>] input_inject_event+0x237/0x280
[<ffffffff843e8c28>] evdev_write+0x478/0x680
[<ffffffff817ac653>] __vfs_write+0x113/0x480
[<ffffffff817ae0e7>] vfs_write+0x167/0x4a0
[<ffffffff817b13d1>] SyS_write+0x111/0x220
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: glider@google.com
Cc: kasan-dev@googlegroups.com
Cc: kcc@google.com
Cc: linux-kernel@vger.kernel.org
Cc: ryabinin.a.a@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/include/asm/processor.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 2d5a50c..20c11d1 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -766,7 +766,7 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk); * Return saved PC of a blocked thread. * What is this good for? it will be always the scheduler or ret_from_fork. */ -#define thread_saved_pc(t) (*(unsigned long *)((t)->thread.sp - 8)) +#define thread_saved_pc(t) READ_ONCE_NOCHECK(*(unsigned long *)((t)->thread.sp - 8)) #define task_pt_regs(tsk) ((struct pt_regs *)(tsk)->thread.sp0 - 1) extern unsigned long KSTK_ESP(struct task_struct *task); |