On Sun, 07 Jan 2018 12:30:53 +0100, Dmitry Vyukov wrote: > > On Thu, Jan 4, 2018 at 6:03 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Thu, 04 Jan 2018 15:17:23 +0100, > > Takashi Iwai wrote: > >> > >> On Thu, 04 Jan 2018 15:01:06 +0100, > >> Dmitry Vyukov wrote: > >> > > >> > On Thu, Jan 4, 2018 at 1:57 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > >> > > On Thu, 04 Jan 2018 13:08:45 +0100, > >> > > Dmitry Vyukov wrote: > >> > >> > >> > >> On Thu, Jan 4, 2018 at 1:03 PM, syzbot > >> > >> <syzbot+387f48da65cb522abfe8@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > >> > >> > Hello, > >> > >> > > >> > >> > syzkaller hit the following crash on > >> > >> > 30a7acd573899fd8b8ac39236eff6468b195ac7d > >> > >> > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master > >> > >> > compiler: gcc (GCC) 7.1.1 20170620 > >> > >> > .config is attached > >> > >> > Raw console output is attached. > >> > >> > Unfortunately, I don't have any reproducer for this bug yet. > >> > >> > > >> > >> > > >> > >> > IMPORTANT: if you fix the bug, please add the following tag to the commit: > >> > >> > Reported-by: syzbot+387f48da65cb522abfe8@xxxxxxxxxxxxxxxxxxxxxxxxx > >> > >> > It will help syzbot understand when the bug is fixed. See footer for > >> > >> > details. > >> > >> > If you forward the report, please keep this part and the footer. > >> > >> > >> > >> This looks ALSA-related. +ALSA maintainers. > >> > > > >> > > Not sure exactly what triggers it. It's the simple memcpy(), and I > >> > > don't know where RCU is involved in that code path. > >> > > > >> > > BTW, other two suspicious RCU usage reports are actually stopped at > >> > > the second WARN_ON() after the RCU message, and the second WARN_ON() > >> > > is independent from RCU; it's the known spurious WARN_ON() and was > >> > > already removed in the sound git tree. > >> > > >> > > >> > Hi Takashi, > >> > > >> > Another similar one just popped up: > >> > > >> > https://groups.google.com/forum/#!topic/syzkaller-bugs/X3d6-PIrJM0 > >> > > >> > This looks like mulaw_decode enters an infinite loop, or at least > >> > doing very large amount of computations without a resched, e.g. > >> > (uint64_t)-1 number of iterations of something along these lines. > >> > >> OK, that makes sense. > >> > >> My rough guess is that it's the misconfigured aloop device by > >> concurrent setup. The aloop device allows to restrict the parameters > >> of the other side of the connection, and something bad may happen > >> there if both sides are updated concurrently. > >> > >> We've seen segfault by memset() at loopback_preapre() in > >> sound/drivers/aloop.c by syzbot+3902b5220e8ca27889ca, too, which > >> indicates also the wrongly setup parameters that overflows the > >> allocated buffer. > > > > Below two patches may possibly plug the holes, but I'm not entirely > > sure whether that's the exact culprit. Could you put them into syzbot > > to watch whether they have any influence? > > Hi Takashi, > > I've gave an answer to this here: > https://groups.google.com/d/msg/syzkaller-bugs/7ucgCkAJKSk/skZjgavRAQAJ OK, noted. > > In anyway, they are obvious bugs to be fixed, so I'm going to queue to > > my tree. > > The options are: > 1. You can ask syzbot to test the patch separately. This requires a > reproducer, but there is this bug which has a reproducer and seems to > have the same root cause: > https://groups.google.com/d/msg/syzkaller-bugs/KrPUlf-nm5g/Vk0xEq-HAAAJ Ah, I didn't know that each bot can test patches individually. > 2. You can reproduce it with the reproducer from here: > https://groups.google.com/d/msg/syzkaller-bugs/KrPUlf-nm5g/Vk0xEq-HAAAJ > and then test the patch as extensively as needed. Yes, I could test and find the culprit with the given reproducer. > 3. If you have some confidence that the patch fixes the problem, then > mark the commit with the tag: > Reported-by: syzbot+387f48da65cb522abfe8@xxxxxxxxxxxxxxxxxxxxxxxxx > then syzbot will notify if this still happens after the commit reaches > tested trees. Some have been already tagged with reported-by. Some are mostly irrelevant but casually found during the debug session for the bugs syzkaller spotted. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
