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x86/unwind: Warn on bad frame pointer

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Detect situations in the unwinder where the frame pointer refers to a
bad address, and print an appropriate warning.

Use printk_deferred_once() because the unwinder can be called with the
console lock by lockdep via save_stack_trace().

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/03c888f6f7414d54fa56b393ea25482be6899b5f.1477496147.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2016-10-26 10:41:48 -05:00 committed by Ingo Molnar
parent bb12d6740f
commit c32c47c68a
1 changed files with 16 additions and 2 deletions
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18
arch/x86/kernel/unwind_frame.c
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@ -123,8 +123,17 @@ bool unwind_next_frame(struct unwind_state *state)
}
/* make sure the next frame's data is accessible */
if (!update_stack_state(state, next_frame, next_len))
return false;
if (!update_stack_state(state, next_frame, next_len)) {
/*
* Don't warn on bad regs->bp. An interrupt in entry code
* might cause a false positive warning.
*/
if (state->regs)
goto the_end;
goto bad_address;
}
/* move to the next frame */
if (regs) {
state->regs = regs;
@ -136,6 +145,11 @@ bool unwind_next_frame(struct unwind_state *state)
return true;
bad_address:
printk_deferred_once(KERN_WARNING
"WARNING: kernel stack frame pointer at %p in %s:%d has bad value %p\n",
state->bp, state->task->comm,
state->task->pid, next_bp);
the_end:
state->stack_info.type = STACK_TYPE_UNKNOWN;
return false;