On Fri, 24 Jun 2016 15:48:53 +0200, Dmitry Vyukov wrote: > > On Fri, Jun 24, 2016 at 3:33 PM, Takashi Iwai <ti...@suse.de> wrote: > > On Tue, 21 Jun 2016 19:41:28 +0200, > > Dmitry Vyukov wrote: > >> > >> On Mon, Jun 6, 2016 at 6:39 PM, Takashi Iwai <ti...@suse.de> wrote: > >> > On Mon, 06 Jun 2016 18:29:25 +0200, > >> > Dmitry Vyukov wrote: > >> >> > >> >> On Mon, Jun 6, 2016 at 4:11 PM, Takashi Iwai <ti...@suse.de> wrote: > >> >> > On Sat, 04 Jun 2016 20:27:50 +0200, > >> >> > Dmitry Vyukov wrote: > >> >> >> > >> >> >> On Sat, Jun 4, 2016 at 8:00 PM, Dmitry Vyukov <dvyu...@google.com> > >> >> >> wrote: > >> >> >> > Hello, > >> >> >> > > >> >> >> > The following program triggers use-after-free: > >> >> >> > >> >> >> Forget to mention that you need to run it in a tight parallel loop. > >> >> >> It > >> >> >> takes around 5 minutes to reproduce for me. > >> >> > > >> >> > Hmm, this again is a bug that is difficult to trigger... At least, I > >> >> > couldn't reproduce locally. How many processes are you running with > >> >> > stress program? > >> >> > >> >> I use a VM with 4 cores and use 20 parallel test processes. > >> >> > >> >> > It seems that there is nothing more than opening /dev/audio and does > >> >> > some mmap in the job. Is there any other relevant thing there? > >> >> > >> >> > >> >> I think poll with timeout is related. It is poll who sets hrtimer, > >> >> right? > >> > > >> > If it's about snd-dummy driver, hrtimer is created at open, and > >> > started/stopped at PCM trigger, and removed at close. > >> > > >> > Is there any good way to decode which syscalls are executed in the > >> > test code? > >> > >> What do you mean? > >> Here are the syscalls in the program: > >> > >> r[2] = syscall(SYS_open, "/dev/audio", 0xa40ul, 0, 0, 0); > >> // r[2] is in the descriptor passed to SYS_poll > >> r[15] = syscall(SYS_poll, 0x2001dde8ul, 0x4ul, 0x8ul, 0, 0, 0); > >> r[18] = syscall(SYS_readv, r[2], 0x20dc13c0ul, 0x1ul, 0, 0, 0); > >> r[19] = syscall(SYS_read, r[2], 0x20dbefe0ul, 0x20ul, 0, 0, 0); > > > > I meant some nice way to decode these magic numbers to be more > > understandable :) > > Short term, run it under strace. It should show file names, decode > most of flags and structs.
Alright, thanks. Takashi
