WARNING in snd_pcm_plugin_build_mulaw

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 15bc20c6 Merge tag 'tty-5.9-rc3' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1268efb1900000
kernel config: https://syzkaller.appspot.com/x/.config?x=891ca5711a9f1650
dashboard link: https://syzkaller.appspot.com/bug?extid=23b22dc2e0b81cbfcc95
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11a95f41900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11a452f2900000

The issue was bisected to:

commit f3ca3f5b0966cfc2737178cca8a7a65b09991898
Author: Fabio Estevam <fest...@gmail.com>
Date: Fri Mar 27 15:57:21 2020 +0000

dt-bindings: sound: cs42l51: Remove unneeded I2C unit name

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15395f41900000
final oops: https://syzkaller.appspot.com/x/report.txt?x=17395f41900000
console output: https://syzkaller.appspot.com/x/log.txt?x=13395f41900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+23b22d...@syzkaller.appspotmail.com
Fixes: f3ca3f5b0966 ("dt-bindings: sound: cs42l51: Remove unneeded I2C unit name")

------------[ cut here ]------------
WARNING: CPU: 0 PID: 6835 at sound/core/oss/mulaw.c:332 snd_pcm_plugin_build_mulaw+0x4ef/0x6e0 sound/core/oss/mulaw.c:332
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 6835 Comm: syz-executor088 Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1f0/0x31e lib/dump_stack.c:118
panic+0x264/0x7a0 kernel/panic.c:231
__warn+0x227/0x250 kernel/panic.c:600
report_bug+0x1b1/0x2e0 lib/bug.c:198
handle_bug+0x42/0x80 arch/x86/kernel/traps.c:234
exc_invalid_op+0x16/0x40 arch/x86/kernel/traps.c:254
asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
RIP: 0010:snd_pcm_plugin_build_mulaw+0x4ef/0x6e0 sound/core/oss/mulaw.c:332
Code: 0f 0b bb fa ff ff ff eb cd e8 fd e3 2d fb 0f 0b bb fa ff ff ff eb bf e8 ef e3 2d fb 0f 0b bb fa ff ff ff eb b1 e8 e1 e3 2d fb <0f> 0b bb fa ff ff ff eb a3 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c 77
RSP: 0018:ffffc90001ed7950 EFLAGS: 00010293
RAX: ffffffff8647143f RBX: 0000000000000000 RCX: ffff88808dcbc540
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff86471e70 R08: ffffffff864710ee R09: fffff520003daf47
R10: fffff520003daf47 R11: 0000000000000000 R12: 1ffff920003daf45
R13: ffffc90001ed7a18 R14: ffffc90001ed7a28 R15: ffffc90001ed7a28
snd_pcm_plug_format_plugins+0xbbd/0x1640 sound/core/oss/pcm_plugin.c:494
snd_pcm_oss_change_params_locked+0x2c29/0x4410 sound/core/oss/pcm_oss.c:952
snd_pcm_oss_change_params sound/core/oss/pcm_oss.c:1084 [inline]
snd_pcm_oss_make_ready+0x115/0x2b0 sound/core/oss/pcm_oss.c:1143
snd_pcm_oss_sync+0x265/0x900 sound/core/oss/pcm_oss.c:1642
snd_pcm_oss_release+0x119/0x270 sound/core/oss/pcm_oss.c:2546
__fput+0x34f/0x7b0 fs/file_table.c:281
task_work_run+0x137/0x1c0 kernel/task_work.c:141
exit_task_work include/linux/task_work.h:25 [inline]
do_exit+0x5f3/0x1f20 kernel/exit.c:806
do_group_exit+0x161/0x2d0 kernel/exit.c:903
__do_sys_exit_group+0x13/0x20 kernel/exit.c:914
__se_sys_exit_group+0x10/0x10 kernel/exit.c:912
__x64_sys_exit_group+0x37/0x40 kernel/exit.c:912
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x440038
Code: Bad RIP value.
RSP: 002b:00007ffe721a2058 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440038
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf870 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Fabio Estevam]

On Tue, Sep 1, 2020 at 7:08 AM syzbot
<syzbot+23b22d...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 15bc20c6 Merge tag 'tty-5.9-rc3' of git://git.kernel.org/p..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1268efb1900000
> kernel config: https://syzkaller.appspot.com/x/.config?x=891ca5711a9f1650
> dashboard link: https://syzkaller.appspot.com/bug?extid=23b22dc2e0b81cbfcc95
> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11a95f41900000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11a452f2900000
>
> The issue was bisected to:
>
> commit f3ca3f5b0966cfc2737178cca8a7a65b09991898
> Author: Fabio Estevam <fest...@gmail.com>
> Date: Fri Mar 27 15:57:21 2020 +0000
>
> dt-bindings: sound: cs42l51: Remove unneeded I2C unit name
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15395f41900000
> final oops: https://syzkaller.appspot.com/x/report.txt?x=17395f41900000
> console output: https://syzkaller.appspot.com/x/log.txt?x=13395f41900000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+23b22d...@syzkaller.appspotmail.com
> Fixes: f3ca3f5b0966 ("dt-bindings: sound: cs42l51: Remove unneeded I2C unit name")

The conclusion that this commit caused the problem is strange, since
this commit is just a yaml documentation fix.

[Takashi Iwai]

The bisection result must be bogus. And the issue here is harmless,
merely a superfluous WARN_ON(). I'll work on it later.


thanks,

Takashi