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    SubjectRe: x86: warning in unwind_get_return_address
    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

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