On Wed, Dec 19, 2018 at 10:04 AM Manfred Spraul <manf...@colorfullife.com> wrote: > > Hello Dmitry, > > On 12/12/18 11:55 AM, Dmitry Vyukov wrote: > > On Tue, Dec 11, 2018 at 9:23 PM syzbot > > <syzbot+1145ec2e23165570c...@syzkaller.appspotmail.com> wrote: > >> Hello, > >> > >> syzbot found the following crash on: > >> > >> HEAD commit: f5d582777bcb Merge branch 'for-linus' of > >> git://git.kernel... > >> git tree: upstream > >> console output: https://syzkaller.appspot.com/x/log.txt?x=135bc547400000 > >> kernel config: https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23 > >> dashboard link: > >> https://syzkaller.appspot.com/bug?extid=1145ec2e23165570c3ac > >> compiler: gcc (GCC) 8.0.1 20180413 (experimental) > >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16803afb400000 > > +Manfred, this looks similar to the other few crashes related to > > semget$private(0x0, 0x4000, 0x3f) that you looked at. > > I found one unexpected (incorrect?) locking, see the attached patch. > > But I doubt that this is the root cause of the crashes.
But why? These one-off sporadic crashes reported by syzbot looks exactly like a subtle race and your patch touches sem_exit_ns involved in all reports. So if you don't spot anything else, I would say close these 3 reports with this patch (I see you already included Reported-by tags which is great!) and then wait for syzbot reaction. Since we got 3 of them, if it's still not fixed I would expect that syzbot will be able to retrigger this later again. > Any remarks on the patch? > > I would continue to search, and then send a series with all findings. > > -- > > Manfred >