On Wed, 10 Jan 2018 19:58:01 +0100, syzbot wrote: > > Hello, > > syzkaller hit the following crash on > cf1fb158230edce8a0482bfb2e59b9c390477fb6 > 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. > C reproducer is attached > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > for information about syzkaller reproducers > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+7e6ee55011deeebce15d@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. > > audit: type=1400 audit(1515606919.914:7): avc: denied { map } for > pid=3501 comm="syzkaller879499" path="/root/syzkaller879499069" > dev="sda1" ino=16481 > scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 > tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 > WARNING: CPU: 1 PID: 3501 at sound/core/pcm_lib.c:563 muldiv32 > sound/core/pcm_lib.c:563 [inline] > WARNING: CPU: 1 PID: 3501 at sound/core/pcm_lib.c:563 > snd_interval_mulkdiv+0x5a9/0x650 sound/core/pcm_lib.c:756 > Kernel panic - not syncing: panic_on_warn set ... > > CPU: 1 PID: 3501 Comm: syzkaller879499 Not tainted 4.15.0-rc7+ #256 > Hardware name: Google Google Compute Engine/Google Compute Engine, > BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:53 > panic+0x1e4/0x41c kernel/panic.c:183 > __warn+0x1dc/0x200 kernel/panic.c:547 > report_bug+0x211/0x2d0 lib/bug.c:184 > fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178 > fixup_bug arch/x86/kernel/traps.c:247 [inline] > do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296 > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315 > invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1079 > RIP: 0010:muldiv32 sound/core/pcm_lib.c:563 [inline] > RIP: 0010:snd_interval_mulkdiv+0x5a9/0x650 sound/core/pcm_lib.c:756 > RSP: 0018:ffff8801c04c7478 EFLAGS: 00010293 > RAX: ffff8801c05f43c0 RBX: ffff8801c04c7500 RCX: ffffffff841cb1f9 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000000f4240 > RBP: ffff8801c04c74c0 R08: 000000000000009c R09: ffffed00380bc5e3 > R10: 0000000000000013 R11: ffffed00380bc5e2 R12: ffff8801c05e2ec0 > R13: ffff8801c05e2eb4 R14: ffff8801c05e2ec8 R15: ffff8801c05e2ebc > snd_pcm_hw_rule_mulkdiv+0xfd/0x1c0 sound/core/pcm_native.c:2040 > constrain_params_by_rules+0x625/0x11b0 sound/core/pcm_native.c:400 > snd_pcm_hw_refine+0x818/0x1070 sound/core/pcm_native.c:502 > snd_pcm_hw_refine_old_user sound/core/pcm_native.c:3612 [inline] > snd_pcm_common_ioctl+0x7f9/0x1f60 sound/core/pcm_native.c:2922 > snd_pcm_ioctl+0x81/0xb0 sound/core/pcm_native.c:2959 > vfs_ioctl fs/ioctl.c:46 [inline] > do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > SYSC_ioctl fs/ioctl.c:701 [inline] > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 This is yet another superfluous WARN_ON() to be removed. I'm going to queue the fix patch below. thanks, Takashi -- 8< -- From: Takashi Iwai <tiwai@xxxxxxx> Subject: [PATCH] ALSA: pcm: Remove yet superfluous WARN_ON() muldiv32() contains a snd_BUG_ON() (which is morphed as WARN_ON() with debug option) for checking the case of 0 / 0. This would be helpful if this happens only as a logical error; however, since the hw refine is performed with any data set provided by user, the inconsistent values that can trigger such a condition might be passed easily. Actually, syzbot caught this by passing some zero'ed old hw_params ioctl. So, having snd_BUG_ON() there is simply superfluous and rather harmful to give unnecessary confusions. Let's get rid of it. Reported-by: syzbot+7e6ee55011deeebce15d@xxxxxxxxxxxxxxxxxxxxxxxxx Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> --- sound/core/pcm_lib.c | 1 - 1 file changed, 1 deletion(-) diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index db7894bb028c..faa67861cbc1 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -560,7 +560,6 @@ static inline unsigned int muldiv32(unsigned int a, unsigned int b, { u_int64_t n = (u_int64_t) a * b; if (c == 0) { - snd_BUG_ON(!n); *r = 0; return UINT_MAX; } -- 2.15.1 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
