UBSAN: shift-out-of-bounds in extAlloc (2)

Status: upstream: reported C repro on 2024/05/03 13:40
Subsystems: jfs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+13e8cd4926977f8337b6@syzkaller.appspotmail.com
First crash: 825d, last: 23d
Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: BUG: unable to handle kernel paging request in dbAdjTree (log)
Repro: C syz .config
  
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
4eea386a assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ UBSAN: shift-out-of-bounds in extAlloc (2) 2026/05/26 09:19 2026/05/26 09:19 2026/05/26 10:03 c69befb3
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [jfs?] UBSAN: shift-out-of-bounds in extAlloc (2) 4 (10) 2026/04/17 16:20
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream UBSAN: shift-out-of-bounds in extAlloc jfs -1 syz, C error 6605 1049d 1410d 23/29 fixed on 2023/10/12 12:47
linux-6.6 UBSAN: shift-out-of-bounds in extAlloc -1 1 209d 209d 0/2 auto-obsoleted due to no activity on 2026/04/18 15:14
linux-5.15 UBSAN: shift-out-of-bounds in extAlloc (2) origin:upstream -1 syz, C error 1 18d 449d 0/3 upstream: reported C repro on 2025/05/14 03:45
linux-5.15 UBSAN: shift-out-of-bounds in extAlloc origin:upstream -1 syz, C done 217 1053d 1245d 3/3 fixed on 2023/10/20 00:28
linux-6.1 UBSAN: shift-out-of-bounds in extAlloc origin:upstream missing-backport -1 syz, C done 204 478d 1242d 3/3 fixed on 2025/05/02 07:04
▶ ▼ Last patch testing requests (15)
Created Duration User Patch Repo Result
2026/08/05 22:06 25m retest repro upstream error
2026/07/05 05:14 21m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/06/28 23:38 26m retest repro linux-next log
2026/06/03 18:21 21m retest repro upstream error
2026/05/27 19:28 22m retest repro upstream error
2026/04/23 02:00 19m retest repro upstream report log
2026/04/22 21:28 31m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/04/17 16:20 22m tristmd@gmail.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master report log
2026/04/17 10:12 17m tristmd@gmail.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master report log
2026/04/08 17:39 1h29m retest repro linux-next report log
2026/04/08 17:10 1h46m retest repro linux-next report log
2026/03/25 16:33 17m retest repro upstream report log
2025/09/28 02:54 16m xandfury@gmail.com upstream report log
2024/06/01 03:01 23m aha310510@gmail.com patch upstream OK log
2024/05/31 11:08 2h20m aha310510@gmail.com patch upstream OK log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/07/13 21:17 2h23m bisect fix upstream OK (0) job log log
2026/06/12 21:43 2h30m bisect fix upstream OK (0) job log log
2025/12/02 06:40 2h26m bisect fix upstream OK (0) job log log

Sample crash report:
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_extent.c:329:16
shift exponent 64 is too large for 64-bit type 's64' (aka 'long long')
CPU: 0 UID: 0 PID: 5839 Comm: syz-executor260 Tainted: G        W           6.16.0-syzkaller-12063-g37816488247d #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x386/0x410 lib/ubsan.c:494
 extBalloc fs/jfs/jfs_extent.c:329 [inline]
 extAlloc+0xd52/0xfb0 fs/jfs/jfs_extent.c:127
 jfs_get_block+0x346/0xab0 fs/jfs/inode.c:248
 __block_write_begin_int+0x6b2/0x1900 fs/buffer.c:2145
 block_write_begin+0x8a/0x120 fs/buffer.c:2256
 jfs_write_begin+0x35/0x80 fs/jfs/inode.c:300
 generic_perform_write+0x29d/0x8c0 mm/filemap.c:4175
 generic_file_write_iter+0x118/0x550 mm/filemap.c:4318
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x554/0xaa0 fs/read_write.c:686
 ksys_write+0x14b/0x260 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6faea35b99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffda611b258 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f6faea35b99
RDX: 00000000fffffdef RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007f6faeaae5f0 R08: 0000555587b974c0 R09: 0000555587b974c0
R10: 0000555587b974c0 R11: 0000000000000246 R12: 00007ffda611b280
R13: 00007ffda611b4a8 R14: 431bde82d7b634db R15: 00007f6faea7e03b
 </TASK>
---[ end trace ]---

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/08 20:05 upstream 37816488247d 32a0e5ed .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs UBSAN: shift-out-of-bounds in extAlloc
2025/08/08 14:54 upstream bec077162bd0 56444e07 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2024/05/03 13:30 linux-next 9221b2819b8a 375d4445 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in extAlloc
2024/05/11 11:51 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci fda5695d692c 9026e142 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in extAlloc
2025/12/16 20:59 upstream 40fbbd64bba6 d1b870e1 .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2026/05/13 18:48 upstream 1d5dcaa3bd65 fec2a7ee .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2026/02/25 15:13 upstream 7dff99b35460 c162cde9 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2025/12/16 20:05 upstream 40fbbd64bba6 d1b870e1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2025/09/10 15:12 upstream 9dd1835ecda5 fdeaa69b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2025/08/08 14:22 upstream bec077162bd0 56444e07 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2025/01/10 10:16 upstream 643e2e259c2b 67d7ec0a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2024/12/25 00:21 upstream 9b2ffa6148b1 444551c4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in extAlloc
2024/05/03 12:50 linux-next 9221b2819b8a 375d4445 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in extAlloc
* Struck through repros no longer work on HEAD.