Re: stack frame unwindind KASAN errors

From	Daniel J Blueman <daniel@quora.org>
Newsgroups	linux.kernel
Subject	Re: stack frame unwindind KASAN errors
Date	2017-03-07 03:10 +0100
Message-ID	<ticJz-ns-5@gated-at.bofh.it> (permalink)
References	<tfmm5-Zq-9@gated-at.bofh.it> <tfwEO-8dT-27@gated-at.bofh.it> <thUWm-4mz-5@gated-at.bofh.it> <ti49j-2x3-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 7 March 2017 at 00:40, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Mon, Mar 06, 2017 at 02:52:01PM +0800, Daniel J Blueman wrote:
>> Thanks Josh!
>>
>> With this patch, the KASAN warning still occurs, but at
>> unwind_get_return_address+0x1d3/0x130 instead; the rest of the trace
>> is identical.
>>
>> (gdb) list *(unwind_get_return_address+0x1d3)
>> 0xffffffff8112bca3 is in unwind_get_return_address
>> (./include/linux/compiler.h:243).
>> 238    })
>> 239
>> 240    static __always_inline
>> 241    void __read_once_size(const volatile void *p, void *res, int size)
>> 242    {
>> 243        __READ_ONCE_SIZE;
>
> Looking deeper, I have an idea about what's going on:
>
>   https://quora.org/dmesg.txt
>
> Each of the warnings seems to show an interrupt happening during an EFI
> call.  I'm guessing EFI modified the frame pointer, at least
> temporarily, which confused the unwinder :-(
>
> Would it be possible for you to test again with 4.10?  It has some
> additional unwinder output which should hopefully confirm my suspicions.

Very good; I don't see the KASAN warnings with 4.10 in the same environment.

Thanks,
  Daniel
-- 
Daniel J Blueman

Thread

Re: stack frame unwindind KASAN errors Daniel J Blueman <daniel@quora.org> - 2017-03-06 08:10 +0100
  Re: stack frame unwindind KASAN errors Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-06 18:00 +0100
    Re: stack frame unwindind KASAN errors Daniel J Blueman <daniel@quora.org> - 2017-03-07 03:10 +0100
      Re: stack frame unwindind KASAN errors Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-07 15:40 +0100

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