On Thu, 21 Apr 2016 10:14:10 +0200, Dmitry Vyukov wrote: > > On Wed, Apr 20, 2016 at 12:31 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Wed, 20 Apr 2016 10:08:55 +0200, > > Takashi Iwai wrote: > >> > >> On Wed, 20 Apr 2016 09:56:04 +0200, > >> Dmitry Vyukov wrote: > >> > > >> > On Sun, Apr 3, 2016 at 8:33 AM, Takashi Iwai <tiwai@xxxxxxx> wrote: > >> > >> >> It is not easily reproducible. I've hit several times while running > >> > >> >> fuzzer for a week. Here is one of the logs for the record: > >> > >> >> https://gist.githubusercontent.com/dvyukov/c84798ee55721563ecb537c4d51dc9f5/raw/f00b865a85877656f13b41917f7321730f140d35/gistfile1.txt > >> > >> > > >> > >> > There are a few more fixes in sound/core/timer.c since 4.5, and they > >> > >> > possibly already cover this. > >> > >> > > >> > >> > Please let me know if this is still seen on the upcoming 4.6-rc2. > >> > >> > >> > >> Hi Takashi, > >> > >> > >> > >> I've updated fuzzer to 05cf8077e54b20dddb756eaa26f3aeb5c38dd3cf (Apr > >> > >> 1) yesterday. Let's see if it still happens. > >> > >> > >> > >> Out of curiosity, how was the bug found? > >> > > > >> > > Well, I'm not entirely sure whether they really cover. It's just a > >> > > hope, as these are patches to close some possible races :) > >> > > > >> > > 9984d1b5835ca29fc7025186a891ee7398d21cc7 > >> > > ALSA: timer: Protect the whole snd_timer_close() with open race > >> > > f65e0d299807d8a11812845c972493c3f9a18e10 > >> > > ALSA: timer: Call notifier in the same spinlock > >> > > 4a07083ed613644c96c34a7dd2853dc5d7c70902 > >> > > ALSA: timer: Use mod_timer() for rearming the system timer > >> > > >> > > >> > Hi Takashi, > >> > > >> > I've hit it again on 806fdcce017dc98c4dbf8ed001750a0d7d2bb0af (Apr > >> > 14), all 3 commits are already in my tree. > >> > > >> > [ 343.222218] ------------[ cut here ]------------ > >> > [ 343.222218] WARNING: CPU: 3 PID: 7040 at kernel/time/hrtimer.c:837 > >> > hrtimer_forward+0x26a/0x3e0 > >> > >> This is a different warning. The previous was use-after-free, and > >> this is a warning about re-arming the queued hrtimer. > >> Maybe there is a slightly remaining race about hrtimer_start() and the > >> interrupt handler in snd-hrtimer. > > > > Could you check whether two patches below help anything? > > This should harden against the race between hrtimer callback and > > another start/stop calls. > > I don't have a reliable way to reproduce it. I've tried to replay the > logs for hours, but no success. And I've hit it only three times: > > -rw-r----- 1 346004 Apr 19 02:36 crash-qemu-23-1461026201572599961 > -rw-r----- 1 393438 Mar 27 08:24 crash-qemu-8-1459059850150353721 > -rw-r----- 1 393439 Mar 10 19:44 crash-qemu-16-1457635446972474955 > > I will merge the patches and restart the fuzzer. It will be difficult > to conclude whether it fixes the bug or not, but at least it will test > the patches. Thanks! I'll test the patches for a while and merge for 4.7 if no regression is found, too. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
