The bug has been already fixed, but unfortunately my submission didn't go out to ML due to some SMPT server problem. (So now I'm using a different system, hopefully it goes out somehow, sorry for the top-post due to that...) I'll resend the patch later, but the fix is found in for-linus branch commit ae352822321d2e8eb17347ab4eb64e461bea6971. https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/commit/?h=for-linus&id=ae352822321d2e8eb17347ab4eb64e461bea6971 Takashi ________________________________ From: Dongliang Mu <mudongliangabcd@xxxxxxxxx> Sent: Wednesday, June 2, 2021 3:18 PM To: allen.lkml@xxxxxxxxx <allen.lkml@xxxxxxxxx>; alsa-devel@xxxxxxxxxxxxxxxx <alsa-devel@xxxxxxxxxxxxxxxx>; Joe Perches <joe@xxxxxxxxxxx>; linux-kernel <linux-kernel@xxxxxxxxxxxxxxx>; perex@xxxxxxxx <perex@xxxxxxxx>; pierre-louis.bossart@xxxxxxxxxxxxxxx <pierre-louis.bossart@xxxxxxxxxxxxxxx>; romain.perier@xxxxxxxxx <romain.perier@xxxxxxxxx>; syzkaller-bugs <syzkaller-bugs@xxxxxxxxxxxxxxxx>; Takashi Iwai <tiwai@xxxxxxxx> Subject: [syzbot] UBSAN: shift-out-of-bounds in snd_timer_user_ccallback > Hello, > > syzbot found the following issue on: > > HEAD commit: 5ff2756a Merge tag 'nfs-for-5.13-2' of git://git.linux-nfs.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=17872d5bd00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=770708ea7cfd4916 > dashboard link: https://syzkaller.appspot.com/bug?extid=d102fa5b35335a7e544e > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+d102fa...@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================================ > UBSAN: shift-out-of-bounds in sound/core/timer.c:1376:23 > shift exponent 105 is too large for 32-bit type 'int' > CPU: 1 PID: 10368 Comm: syz-executor.1 Not tainted 5.13.0-rc3-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x141/0x1d7 lib/dump_stack.c:120 > ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 > __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327 > snd_timer_user_ccallback.cold+0x19/0x1e sound/core/timer.c:1376 > > snd_timer_notify1+0x243/0x3b0 sound/core/timer.c:525 The root cause of this bug is in the snd_timer_notify1 [1]. At the end of this function, it calls "ts->ccallback(ts, event + 100, &tstamp, resolution)". Here the variable event is 5. It adds 100 and is passed as 2nd argument of snd_timer_user_ccallback. >From the variable naming, the 2nd argument should an event, and in the range of event enumeration. In fact, 105 (event + 100) is out of this range. I don't quite understand the meaning of adding 100. Any thought here? [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/core/timer.c?id=5ff2756afde08b266fbb673849899fec694f39f1#n497 -- My best regards to you. No System Is Safe! Dongliang Mu
