Messages in this thread | | | Date | Fri, 4 Jan 2019 18:14:24 +0100 | From | Stefano Brivio <> | Subject | Re: kernel panic: stack is corrupted in udp4_lib_lookup2 |
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On Fri, 4 Jan 2019 12:05:04 +0100 Dmitry Vyukov <dvyukov@google.com> wrote:
> On Fri, Jan 4, 2019 at 11:54 AM Stefano Brivio <sbrivio@redhat.com> wrote: > > > > On Fri, 4 Jan 2019 11:32:12 +0100 > > Dmitry Vyukov <dvyukov@google.com> wrote: > > > > > On Thu, Jan 3, 2019 at 10:54 PM Stefano Brivio <sbrivio@redhat.com> wrote: > > > > > > > > On Thu, 3 Jan 2019 15:15:06 -0600 > > > > Willem de Bruijn <willemdebruijn.kernel@gmail.com> wrote: > > > > > > > > > syzbot generated stack traces with > > > > > > > > > > [ 183.517380] udpv6_err+0x46/0x60 > > > > > [ 183.520739] ? __udp6_lib_err+0x1890/0x1890 > > > > > [ 183.525054] gue6_err_proto_handler+0x199/0x280 > > > > > > > > Where? I can't find that in any logs linked from the dashboard at > > > > https://syzkaller.appspot.com/bug?extid=4ad25edc7a33e4ab91e0 :( > > > > > > Stefano, there are these 4 bugs reported that have similarly looking > > > reproducers involving udp sockets and that crash modes that looks like > > > stack corruption/overflow: > > > > > > https://syzkaller.appspot.com/bug?extid=14005fa30c9a07192934 > > > https://syzkaller.appspot.com/bug?extid=d14090007dc9ba5fa9b7 > > > https://syzkaller.appspot.com/bug?extid=137ed32ec9a6d5b0d5fe > > > https://syzkaller.appspot.com/bug?id=d5bc3e0c66d200d72216ab343a67c4327e4a3452 > > > > > > Are these the same bug as this? > > > > Judging from the reproducers for the first three, they seem to be. > > OK, then I will mark them as dups of this one.
syzbot just finished the tests I requested and couldn't reproduce the first three issues with the fix I posted (fou6: Prevent unbounded recursion in GUE error handler).
This should prove they are in fact the same issue.
> > I > > guess I can trigger tests also for those by sending a (sharp)syz > > test ... e-mail with the patch to the Reported-by: addresses, right? > > Correct. > These should be on LKML, but as you noted you can just add the syzbot > email with tag to TO/CC. That email is available in the Reported-by > tag (and also shown on the dashboard).
Okay, thanks for confirming.
> > And the three reports you pointed out from the pile of corrupted > > reports also seem to match, others look unrelated. > > I've added these as tests: > > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/341 > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/342 > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/343 > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/344 > > Will try to figure out how to distinguish them from true corrupted > reports. Usually when Call Trace does not have any frames, it's a sign > of a corrupted report, and in other crashes we see the same report but > with a stack trace. But some stack-corruption-related reliably don't > have stack traces (not corrupted). But then some other > stack-corruption-related crashes do have stack traces, and for these > no stack trace again means a corrupted kernel output. Amusingly this > is one of the most complex parts of syzkaller.
I'm not sure how complicated that would be, but what about some metric based on valid symbol names being reported?
-- Stefano
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