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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2017-01-09 21:00:23 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-01-12 11:28:27 +0300 |
| commit | 84936118bdf37bda513d4a361c38181a216427e0 (patch) | |
| tree | 811f0e8e4c6776d12e7315c076a12a32c3ecf093 /arch/x86/include | |
| parent | 900742d89c1b4e04bd373aec8470b88e183f08ca (diff) | |
| download | linux-84936118bdf37bda513d4a361c38181a216427e0.tar.xz | |
x86/unwind: Disable KASAN checks for non-current tasks
There are a handful of callers to save_stack_trace_tsk() and
show_stack() which try to unwind the stack of a task other than current.
In such cases, it's remotely possible that the task is running on one
CPU while the unwinder is reading its stack from another CPU, causing
the unwinder to see stack corruption.
These cases seem to be mostly harmless. The unwinder has checks which
prevent it from following bad pointers beyond the bounds of the stack.
So it's not really a bug as long as the caller understands that
unwinding another task will not always succeed.
In such cases, it's possible that the unwinder may read a KASAN-poisoned
region of the stack. Account for that by using READ_ONCE_NOCHECK() when
reading the stack of another task.
Use READ_ONCE() when reading the stack of the current task, since KASAN
warnings can still be useful for finding bugs in that case.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/4c575eb288ba9f73d498dfe0acde2f58674598f1.1483978430.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/stacktrace.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h index a3269c897ec5..20ce3db20f24 100644 --- a/arch/x86/include/asm/stacktrace.h +++ b/arch/x86/include/asm/stacktrace.h @@ -52,13 +52,16 @@ static inline bool on_stack(struct stack_info *info, void *addr, size_t len) static inline unsigned long * get_frame_pointer(struct task_struct *task, struct pt_regs *regs) { + struct inactive_task_frame *frame; + if (regs) return (unsigned long *)regs->bp; if (task == current) return __builtin_frame_address(0); - return (unsigned long *)((struct inactive_task_frame *)task->thread.sp)->bp; + frame = (struct inactive_task_frame *)task->thread.sp; + return (unsigned long *)READ_ONCE_NOCHECK(frame->bp); } #else static inline unsigned long * |