UBSAN: array-index-out-of-bounds in snd_dummy_probe

Status: upstream: reported C repro on 2026/08/05 22:46
Subsystems: sound
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+2fb5d1f7cc4c1f132bcc@syzkaller.appspotmail.com
Fix commit: ALSA: dummy: Check card index validity at probe
Patched on: [ci-upstream-linux-next-kasan-gce-root], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 9d03h, last: 8d21h
▶ ▼ ✨ AI Patch Versions (1)
Version Stage Reported Report Link Job
1 moderation 2026/08/07 06:30 Discussion 420b7754-7b1e-46a8-bbc3-9b77df287d5d
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
420b7754 patching ❓ UBSAN: array-index-out-of-bounds in snd_dummy_probe 2026/08/06 06:48 2026/08/07 05:21 2026/08/07 06:30 c38879ea
948540f2 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ UBSAN: array-index-out-of-bounds in snd_dummy_probe 2026/08/06 06:48 2026/08/07 04:50 2026/08/07 05:21 c38879ea
e21147ab assessment-security 💥 UBSAN: array-index-out-of-bounds in snd_dummy_probe 2026/08/05 00:02 2026/08/05 00:02 2026/08/05 00:02 d4abbeac
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [sound?] UBSAN: array-index-out-of-bounds in snd_dummy_probe 0 (2) 2026/08/06 12:25
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 UBSAN: array-index-out-of-bounds in snd_dummy_probe 15 syz, C 3 4d12h 8d19h 0/2 upstream: reported C repro on 2026/08/04 21:14
linux-6.1 UBSAN: array-index-out-of-bounds in snd_dummy_probe 15 syz, C 2 3d19h 8d15h 0/3 upstream: reported C repro on 2026/08/05 01:16
linux-5.15 UBSAN: array-index-out-of-bounds in snd_dummy_probe 15 syz, C 3 4d16h 8d20h 0/3 upstream: reported C repro on 2026/08/04 20:34
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/06 12:25 3h20m sajal2005gupta@gmail.com patch upstream OK log

Sample crash report:
------------[ cut here ]-[   99.286460][ T5617] ------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in sound/drivers/dummy.c:1020:40
index -1 is out of range for type 'int[8]'
CPU: 0 UID: 0 PID: 5617 Comm: syz-executor633 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_out_of_bounds+0xe8/0xf0 lib/ubsan.c:455
 snd_dummy_probe+0x12c6/0x18f0 sound/drivers/dummy.c:1020
 platform_probe+0xf9/0x190 drivers/base/platform.c:1439
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:706
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
 device_driver_attach+0xe0/0x1d0 drivers/base/dd.c:1203
 bind_store+0x1d3/0x220 drivers/base/bus.c:267
 kernfs_fop_write_iter+0x3a5/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61e/0xbb0 fs/read_write.c:687
 ksys_write+0x156/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f978d6bd609
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc5d9d4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f978d6bd609
RDX: 0000000000000007 RSI: 0000200000000180 RDI: 0000000000000004
RBP: 0000000000000001 R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 00007ffc5d9d4198
R13: 0000200000000004 R14: 00007f978d750c40 R15: 0000000000000002
 </TASK>
---[ end trace ]---

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/04 18:35 upstream 848acc8ffe1b d4abbeac .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 18:12 upstream 848acc8ffe1b d4abbeac .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 16:04 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 16:03 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 14:36 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 14:36 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 13:55 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 13:54 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 13:24 upstream 848acc8ffe1b 3c5eaa21 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 13:23 upstream 848acc8ffe1b 3c5eaa21 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 17:32 upstream 848acc8ffe1b 3c5eaa21 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 17:31 upstream 848acc8ffe1b 3c5eaa21 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 19:22 linux-next cc2b5f627e8c d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce UBSAN: array-index-out-of-bounds in snd_dummy_probe
2026/08/04 19:21 linux-next cc2b5f627e8c d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce UBSAN: array-index-out-of-bounds in snd_dummy_probe
* Struck through repros no longer work on HEAD.