[moderation] [sound?] BUG: unable to handle kernel NULL pointer dereference in snd_ctl_led_get

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 94515f3a7d42 Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1209ecb9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1306985a600de748
dashboard link: https://syzkaller.appspot.com/bug?extid=618c20ee2c4c380eb2dd
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
CC: [linux-...@vger.kernel.org linux...@vger.kernel.org pe...@perex.cz ti...@suse.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fa80546e7842/disk-94515f3a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/048475c8e046/vmlinux-94515f3a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2fa1a7896f8c/bzImage-94515f3a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+618c20...@syzkaller.appspotmail.com

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 800000007f1a7067 P4D 800000007f1a7067 PUD 0
Oops: Oops: 0010 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 19192 Comm: syz.3.4383 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc90005177940 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88807f320000 RCX: 0000000000000000
RDX: 1ffff1100fe6400c RSI: ffffffff9bb6b200 RDI: ffff88807f320000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff9bb6b200 R11: 0000000000000000 R12: 000000000000000a
R13: ffff88801f760c00 R14: ffff88807f320000 R15: ffffffff90960a28
FS: 00007f010f2d76c0(0000) GS:ffff888123dee000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000006a612000 CR4: 00000000003526f0
Call Trace:
<TASK>
snd_ctl_led_get+0x231/0x430 sound/core/control_led.c:122
snd_ctl_led_set_state+0x5c1/0x7f0 sound/core/control_led.c:168
snd_ctl_led_notify+0x15b/0x1e0 sound/core/control_led.c:239
snd_ctl_led_set_id sound/core/control_led.c:268 [inline]
set_led_id+0xb0f/0xe80 sound/core/control_led.c:557
dev_attr_store+0x58/0x80 drivers/base/core.c:2505
sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f010e39de99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f010f2d7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f010e625fa0 RCX: 00007f010e39de99
RDX: 0000000000000002 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f010e433eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f010e626038 R14: 00007f010e625fa0 R15: 00007ffd681ba4d8
</TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc90005177940 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88807f320000 RCX: 0000000000000000
RDX: 1ffff1100fe6400c RSI: ffffffff9bb6b200 RDI: ffff88807f320000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff9bb6b200 R11: 0000000000000000 R12: 000000000000000a
R13: ffff88801f760c00 R14: ffff88807f320000 R15: ffffffff90960a28
FS: 00007f010f2d76c0(0000) GS:ffff888123dee000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000006a612000 CR4: 00000000003526f0


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[Alexander Potapenko]

#syz upstream