Re: [syzbot] [sound?] BUG: unable to handle kernel paging request in snd_hdac_bus_parse_capabilities

From: syzbot

Date: Wed Aug 12 2026 - 06:31:25 EST


syzbot has found a reproducer for the following issue on:

HEAD commit: f5bbbfec59b4 Merge tag 'probes-fixes-v7.2-rc7' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=142eb479580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c44651ea7dd2f307
dashboard link: https://syzkaller.appspot.com/bug?extid=10cd2d1efe8eeb604bee
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=103a1149580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+10cd2d1efe8eeb604bee@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: unable to handle page fault for address: 000000000001c0b4
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP KASAN NOPTI
CPU: 1 UID: 0 PID: 1039 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events azx_probe_work
RIP: 0010:readw arch/x86/include/asm/io.h:58 [inline]
RIP: 0010:snd_hdac_reg_readw include/sound/hdaudio.h:458 [inline]
RIP: 0010:snd_hdac_bus_parse_capabilities+0x42/0x6d0 sound/hda/core/controller.c:412
Code: 97 f8 48 8d 45 20 48 89 c2 48 89 44 24 10 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 f8 05 00 00 48 8b 45 20 <66> 44 8b 68 14 4c 8b 7c 24 10 48 89 e8 45 0f b7 ed 45 31 f6 48 ba
RSP: 0018:ffffc90005537ab0 EFLAGS: 00010246
RAX: 000000000001c0a0 RBX: ffff888027304058 RCX: ffffffff897e8c06
RDX: 1ffff11004e6080b RSI: ffffffff8972cfca RDI: ffff888027304038
RBP: ffff888027304038 R08: 0000000000000005 R09: 0000000000000003
R10: 0000000000000003 R11: 000000000000759b R12: 0000000000000003
R13: ffff8880294e4f44 R14: ffff888022d6c000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880d5eec000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000001c0b4 CR3: 000000005526e000 CR4: 0000000000352ef0
Call Trace:
<TASK>
azx_first_init sound/hda/controllers/intel.c:1936 [inline]
azx_probe_continue sound/hda/controllers/intel.c:2365 [inline]
azx_probe_work+0x1d8e/0x2640 sound/hda/controllers/intel.c:1737
process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
CR2: 000000000001c0b4
---[ end trace 0000000000000000 ]---
RIP: 0010:readw arch/x86/include/asm/io.h:58 [inline]
RIP: 0010:snd_hdac_reg_readw include/sound/hdaudio.h:458 [inline]
RIP: 0010:snd_hdac_bus_parse_capabilities+0x42/0x6d0 sound/hda/core/controller.c:412
Code: 97 f8 48 8d 45 20 48 89 c2 48 89 44 24 10 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 f8 05 00 00 48 8b 45 20 <66> 44 8b 68 14 4c 8b 7c 24 10 48 89 e8 45 0f b7 ed 45 31 f6 48 ba
RSP: 0018:ffffc90005537ab0 EFLAGS: 00010246
RAX: 000000000001c0a0 RBX: ffff888027304058 RCX: ffffffff897e8c06
RDX: 1ffff11004e6080b RSI: ffffffff8972cfca RDI: ffff888027304038
RBP: ffff888027304038 R08: 0000000000000005 R09: 0000000000000003
R10: 0000000000000003 R11: 000000000000759b R12: 0000000000000003
R13: ffff8880294e4f44 R14: ffff888022d6c000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880d5eec000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000001c0b4 CR3: 000000005526e000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
0: 97 xchg %eax,%edi
1: f8 clc
2: 48 8d 45 20 lea 0x20(%rbp),%rax
6: 48 89 c2 mov %rax,%rdx
9: 48 89 44 24 10 mov %rax,0x10(%rsp)
e: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
15: fc ff df
18: 48 c1 ea 03 shr $0x3,%rdx
1c: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
20: 0f 85 f8 05 00 00 jne 0x61e
26: 48 8b 45 20 mov 0x20(%rbp),%rax
* 2a: 66 44 8b 68 14 mov 0x14(%rax),%r13w <-- trapping instruction
2f: 4c 8b 7c 24 10 mov 0x10(%rsp),%r15
34: 48 89 e8 mov %rbp,%rax
37: 45 0f b7 ed movzwl %r13w,%r13d
3b: 45 31 f6 xor %r14d,%r14d
3e: 48 rex.W
3f: ba .byte 0xba


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