Messages in this thread | | | Date | Thu, 16 Jun 2016 13:16:42 -0500 | From | Josh Poimboeuf <> | Subject | Re: [PATCH 10/13] x86/dumpstack: Try harder to get a call trace on stack overflow |
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On Wed, Jun 15, 2016 at 05:28:32PM -0700, Andy Lutomirski wrote: > If we overflow the stack, print_context_stack will abort. Detect > this case and rewind back into the valid part of the stack so that > we can trace it. > > Signed-off-by: Andy Lutomirski <luto@kernel.org> > --- > arch/x86/kernel/dumpstack.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c > index d4d085e27d04..400a2e17c1d1 100644 > --- a/arch/x86/kernel/dumpstack.c > +++ b/arch/x86/kernel/dumpstack.c > @@ -100,6 +100,13 @@ print_context_stack(struct thread_info *tinfo, > { > struct stack_frame *frame = (struct stack_frame *)bp; > > + /* > + * If we overflowed the stack into a guard page, jump back to the > + * bottom of the usable stack. > + */ > + if ((unsigned long)tinfo - (unsigned long)stack < PAGE_SIZE) > + stack = (unsigned long *)tinfo + 1;
That will start walking the stack in the middle of the thread_info struct.
I think you meant:
stack = (unsigned long *)(tinfo + 1)
However, thread_info will have been overwritten anyway. So maybe it should just be:
stack = tinfo;
(Though that still wouldn't quite work because the valid_stack_ptr() check would fail...)
> + > while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) { > unsigned long addr;
-- Josh
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