On Sun, Apr 3, 2016 at 8:33 AM, Takashi Iwai tiwai@suse.de 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/...
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
- 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 [ 343.222218] Modules linked in: [ 343.222218] CPU: 3 PID: 7040 Comm: syz-executor Not tainted 4.6.0-rc3+ #349 [ 343.222218] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [ 343.229525] ffffffff87eb25c0 ffff88006d507ce0 ffffffff82c8fabf ffffffff86abac00 [ 343.229525] fffffbfff0fd64b8 0000000000000000 0000000000000000 ffffffff86abac00 [ 343.229525] ffffffff814cfe1a 0000000000000009 ffff88006d507d28 ffffffff8136639f [ 343.229525] Call Trace: [ 343.229525] <IRQ> [<ffffffff82c8fabf>] dump_stack+0x12e/0x18f [ 343.229525] [<ffffffff814cfe1a>] ? hrtimer_forward+0x26a/0x3e0 [ 343.229525] [<ffffffff8136639f>] __warn+0x19f/0x1e0 [ 343.229525] [<ffffffff813665ac>] warn_slowpath_null+0x2c/0x40 [ 343.229525] [<ffffffff814cfe1a>] hrtimer_forward+0x26a/0x3e0 [ 343.229525] [<ffffffff85382ceb>] snd_hrtimer_callback+0x11b/0x230 [ 343.229525] [<ffffffff814d1091>] __hrtimer_run_queues+0x331/0xe90 [ 343.229525] [<ffffffff85382bd0>] ? snd_hrtimer_close+0xa0/0xa0 [ 343.229525] [<ffffffff814d0d60>] ? enqueue_hrtimer+0x3d0/0x3d0 [ 343.229525] [<ffffffff814d3a62>] hrtimer_interrupt+0x182/0x430 [ 343.229525] [<ffffffff8125aa52>] local_apic_timer_interrupt+0x72/0xe0 [ 343.229525] [<ffffffff867bec99>] smp_apic_timer_interrupt+0x79/0xa0 [ 343.229525] [<ffffffff867bcfec>] apic_timer_interrupt+0x8c/0xa0 [ 343.229525] <EOI> [<ffffffff813e2e00>] ? ___might_sleep+0x3a0/0x3a0 [ 343.229525] [<ffffffff81710fbf>] ? __might_fault+0xaf/0x1d0 [ 343.229525] [<ffffffff814d4f4d>] SyS_nanosleep+0x6d/0x100 [ 343.229525] [<ffffffff814d4ee0>] ? hrtimer_nanosleep+0x730/0x730 [ 343.229525] [<ffffffff81007b53>] ? syscall_trace_enter_phase2+0x143/0x740 [ 343.229525] [<ffffffff81008758>] ? do_syscall_64+0x48/0x640 [ 343.229525] [<ffffffff8100821b>] ? syscall_trace_enter+0xcb/0xf0 [ 343.229525] [<ffffffff814d4ee0>] ? hrtimer_nanosleep+0x730/0x730 [ 343.229525] [<ffffffff810088ef>] do_syscall_64+0x1df/0x640 [ 343.229525] [<ffffffff8100501b>] ? trace_hardirqs_on_thunk+0x1b/0x1d [ 343.229525] [<ffffffff867bc443>] entry_SYSCALL64_slow_path+0x25/0x25 [ 343.229525] ---[ end trace f4fa4ed5ea230466 ]---
For the record, here is syzkaller log: https://gist.githubusercontent.com/dvyukov/4c31022a284421020029c877561a99ed/...