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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Kostya Serebryany <kcc@google.com>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: x86: warning in unwind_get_return_address
Date: Tue, 20 Dec 2016 17:36:40 -0600	[thread overview]
Message-ID: <20161220233640.pc4goscldmpkvtqa@treble> (raw)
In-Reply-To: <CAAeHK+z7O-byXDL4AMZP5TdeWHSbY-K69cbN6EeYo5eAtvJ0ng@mail.gmail.com>

On Tue, Dec 20, 2016 at 11:35:23PM +0100, Andrey Konovalov wrote:
> On Tue, Dec 20, 2016 at 10:01 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Tue, Dec 20, 2016 at 03:43:27PM +0100, Andrey Konovalov wrote:
> >> Hi,
> >>
> >> I've got the following warning while running the syzkaller fuzzer:
> >>
> >> WARNING: unrecognized kernel stack return address ffffffffa0000001 at
> >> ffff88006377fa18 in a.out:4467
> >>
> >> By adding a BUG() to unwind_get_return_address() I was able to capture
> >> the stack trace (see below). Looks like unwind_get_return_address()
> >> gets called when KASAN tries to unwind the stack to save the stack
> >> trace.
> >>
> >> A reproducer is attached. CONFIG_KASAN=y is most likely needed for it to work.
> >
> > Hi Andrey,
> >
> > I've tried with your reproducer but it didn't recreate.  Can you try
> > again with the following patch from the tip tree, instead of your BUG()
> > patch?
> >
> >   http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/patch/?id=8b5e99f02264130782a10ba5c0c759797fb064ee
> >
> > That will dump the stack data, which should give more clues about what
> > went wrong.
> 
> Hi Josh,
> 
> Sure, here it is:

Thanks.  Looking at the stack trace, my guess is that an interrupt hit
while running in generated BPF code, and the unwinder got confused
because regs->ip points to the generated code.  I may need to disable
that warning until we figure out a better solution.

Can you share your .config file?

-- 
Josh

  reply	other threads:[~2016-12-20 23:36 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-20 14:43 x86: warning in unwind_get_return_address Andrey Konovalov
2016-12-20 21:01 ` Josh Poimboeuf
2016-12-20 22:35   ` Andrey Konovalov
2016-12-20 23:36     ` Josh Poimboeuf [this message]
2016-12-21 12:46       ` Andrey Konovalov
2016-12-22  5:17         ` Josh Poimboeuf
2016-12-27 16:38           ` Dmitry Vyukov
2017-01-05 14:49             ` Josh Poimboeuf
2017-01-05 14:59               ` Dmitry Vyukov
2017-01-05 15:17                 ` Josh Poimboeuf
2017-01-05 17:03                   ` Josh Poimboeuf
2017-01-05 20:23                     ` Dmitry Vyukov
2017-01-05 20:37                       ` Josh Poimboeuf

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