Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbAllocAG (3)

syzbot
2026-04-17T17:36:03Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
kernel BUG in jfs_evict_inode

------------[ cut here ]------------
kernel BU[ 188.761535][ T6320] kernel BUG at fs/jfs/inode.c:175!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6320 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:jfs_evict_inode+0x438/0x440 fs/jfs/inode.c:175
Code: fe e9 e0 fd ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 23 fe ff ff 4c 89 f7 e8 23 2f de fe e9 16 fe ff ff e8 19 cb 78 fe 90 <0f> 0b 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90003df7aa0 EFLAGS: 00010293
RAX: ffffffff834a3207 RBX: ffff8880648c2138 RCX: ffff8880277e0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff834a0e30 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8880648c1df0 R15: ffff8880648c2138
FS: 0000555561408500(0000) GS:ffff8881263ef000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e1be8c2e20 CR3: 0000000030240000 CR4: 00000000003526f0
Call Trace:
<TASK>
evict+0x61e/0xb10 fs/inode.c:841
dispose_list fs/inode.c:883 [inline]
evict_inodes+0x75a/0x7f0 fs/inode.c:937
generic_shutdown_super+0xaa/0x2d0 fs/super.c:632
kill_block_super+0x44/0x90 fs/super.c:1725
deactivate_locked_super+0xbc/0x130 fs/super.c:476
cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
task_work_run+0x1d9/0x270 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f915143b797
Code: a2 c7 05 fc 6d 23 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fffebc513b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f91514cd33b RCX: 00007f915143b797
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffebc51470
RBP: 00007fffebc51470 R08: 00007fffebc52470 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffebc52500
R13: 00007f91514cd33b R14: 000000000002df84 R15: 00007fffebc52540
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:jfs_evict_inode+0x438/0x440 fs/jfs/inode.c:175
Code: fe e9 e0 fd ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 23 fe ff ff 4c 89 f7 e8 23 2f de fe e9 16 fe ff ff e8 19 cb 78 fe 90 <0f> 0b 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90003df7aa0 EFLAGS: 00010293
RAX: ffffffff834a3207 RBX: ffff8880648c2138 RCX: ffff8880277e0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff834a0e30 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8880648c1df0 R15: ffff8880648c2138
FS: 0000555561408500(0000) GS:ffff8881263ef000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e1be8bbbe0 CR3: 0000000030240000 CR4: 00000000003526f0

Tested on:

commit: d730905b Merge tag 'mips_7.1' of git://git.kernel.org/..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=138e78ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b37958d01fb80f0
dashboard link: https://syzkaller.appspot.com/bug?extid=4b717071f1eecb2972df
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=1393f036580000