UBSAN: array-index-out-of-bounds in super_90_sync

Status: upstream: reported C repro on 2026/09/13 13:09
Subsystems: raid
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+9e3014263a35700ab49b@syzkaller.appspotmail.com
First crash: 4d05h, last: 1h19m
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
79b337ee repro-c Reproduced: ✅ ❓ UBSAN: array-index-out-of-bounds in super_90_sync 2026/09/13 14:07 2026/09/13 14:54 2026/09/13 17:20 70a60e12
3dfb6a43 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ UBSAN: array-index-out-of-bounds in super_90_sync 2026/09/11 00:50 2026/09/11 00:50 2026/09/11 01:29 1fe56c0a
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [raid?] UBSAN: array-index-out-of-bounds in super_90_sync 0 (2) 2026/09/13 17:34
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/09/13 17:20 13m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2f0c1cf72f4682178506f513bbf015e591b1aa4a report job log log

Sample crash report:
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in drivers/md/md.c:1697:17
index 124 is out of range for type 'mdp_disk_t [27]'
CPU: 1 UID: 0 PID: 6018 Comm: syz-executor186 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
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_out_of_bounds+0xcc/0xf0 lib/ubsan.c:455
 super_90_sync+0x1eed/0x1ff0 drivers/md/md.c:1697
 sync_super drivers/md/md.c:2505 [inline]
 sync_sbs drivers/md/md.c:2747 [inline]
 md_update_sb+0xbba/0x2840 drivers/md/md.c:2923
 state_store+0x31e/0x1340 drivers/md/md.c:3245
 rdev_attr_store+0x1d9/0x560 drivers/md/md.c:3768
 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+0x6af/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f84634ad6f7
Code: 48 89 fa 4c 89 df e8 98 1d 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff04c70ef0 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00005555934c5400 RCX: 00007f84634ad6f7
RDX: 0000000000000008 RSI: 00007f84634e9c12 RDI: 0000000000000003
RBP: 00007f84634e9c12 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff04c70fc0
R13: 00007f84634e9b5f R14: 00007fff04c710d0 R15: 0000000000000002
 </TASK>
---[ end trace ]---

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/13 17:33 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2f0c1cf72f46 8387c273 .config console log report C ci-qemu-upstream UBSAN: array-index-out-of-bounds in super_90_sync
2026/09/09 13:09 upstream 893e11787f78 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root UBSAN: array-index-out-of-bounds in super_90_sync
2026/09/09 13:04 upstream 893e11787f78 edec9137 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream UBSAN: array-index-out-of-bounds in super_90_sync
* Struck through repros no longer work on HEAD.