Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone

syzbot
2026-04-17T12:59:02Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in lbmRead

INFO: task syz.0.17:6554 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17 state:D stack:24224 pid:6554 tgid:6552 ppid:6447 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x1681/0x54c0 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7282
lbmRead+0x41d/0x620 fs/jfs/jfs_logmgr.c:1987
lmLogInit+0xc31/0x1a00 fs/jfs/jfs_logmgr.c:1332
open_inline_log fs/jfs/jfs_logmgr.c:1173 [inline]
lmLogOpen+0x4e1/0xfa0 fs/jfs/jfs_logmgr.c:1067
jfs_mount_rw+0xee/0x670 fs/jfs/jfs_mount.c:257
jfs_fill_super+0x754/0xd80 fs/jfs/super.c:532
get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
vfs_get_tree+0x92/0x2a0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
do_new_mount_fc fs/namespace.c:3758 [inline]
do_new_mount+0x341/0xd30 fs/namespace.c:3834
do_mount fs/namespace.c:4167 [inline]
__do_sys_mount fs/namespace.c:4383 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4360
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa8f8bfda8a
RSP: 002b:00007fa8f8255e58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fa8f8255ee0 RCX: 00007fa8f8bfda8a
RDX: 0000200000000400 RSI: 00002000000000c0 RDI: 00007fa8f8255ea0
RBP: 0000200000000400 R08: 00007fa8f8255ee0 R09: 000000000001c802
R10: 000000000001c802 R11: 0000000000000246 R12: 00002000000000c0
R13: 00007fa8f8255ea0 R14: 0000000000005f9a R15: 0000200000002740
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/38:
#0: ffffffff8dfc7f00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8dfc7f00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8dfc7f00 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u9:0/59:
#0: ffff88802a705138 ((wq_completion)hci2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
#0: ffff88802a705138 ((wq_completion)hci2){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
#1: ffffc9000125fc40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
#1: ffffc9000125fc40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
#2: ffff888038d10f80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x1d3/0x400 net/bluetooth/hci_sync.c:331
9 locks held by kworker/u8:11/2867:
2 locks held by getty/5561:
#0: ffff8880389230a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003cbe2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13a0 drivers/tty/n_tty.c:2211
1 lock held by syz.0.17/6554:
#0: ffff8880395e20d0 (&type->s_umount_key#55/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345
1 lock held by syz.1.19/6613:
#0: ffff88804e5d00d0 (&type->s_umount_key#55/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345
1 lock held by syz.2.28/6658:
#0: ffff88805bffc0d0 (&type->s_umount_key#55/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345
2 locks held by syz-executor/6660:
#0: ffff8880587a60d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff8880587a60d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff8880587a60d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508
#1: ffffffff8e4545d8 (jfs_log_mutex){+.+.}-{4:4}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1441
2 locks held by syz-executor/6692:
#0: ffff888035d4e0d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff888035d4e0d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff888035d4e0d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508
#1: ffffffff8e4545d8 (jfs_log_mutex){+.+.}-{4:4}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1441
2 locks held by syz-executor/6720:
#0: ffff88805a2500d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88805a2500d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88805a2500d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508
#1: ffffffff8e4545d8 (jfs_log_mutex){+.+.}-{4:4}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1441
2 locks held by syz-executor/6754:
#0: ffff88803f6220d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88803f6220d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88803f6220d0 (&type->s_umount_key#56){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508
#1: ffffffff8e4545d8 (jfs_log_mutex){+.+.}-{4:4}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1441
1 lock held by syz.7.41/6809:
#0: ffff8880365f80d0 (&type->s_umount_key#55/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345
1 lock held by syz.8.42/6838:
#0: ffff8880399d60d0 (&type->s_umount_key#55/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd3/0x1030 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 2867 Comm: kworker/u8:11 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:reacquire_held_locks+0xf6/0x190 kernel/locking/lockdep.c:5385
Code: e2 01 89 c1 c1 e9 10 83 e1 03 41 89 c0 41 c1 e8 12 41 83 e0 01 41 89 c1 41 c1 e9 13 41 83 e1 01 c1 e8 15 45 8b 16 6a 00 41 52 <50> 41 ff 76 e4 41 ff 76 f4 e8 8c 9f ff ff 48 83 c4 28 83 f8 01 0f
RSP: 0018:ffffc9000e707820 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffffc9000e707884 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8dfc7f00
RBP: 00000000ffffffff R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: fffffbfff1f16d97 R12: 0000000000000004
R13: 0000000000000004 R14: ffff8880324968fc R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88812610f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555dbfc4e8 CR3: 000000000ddb6000 CR4: 00000000003526f0
Call Trace:
<TASK>
__lock_release kernel/locking/lockdep.c:5574 [inline]
lock_release+0x199/0x3c0 kernel/locking/lockdep.c:5889
__local_bh_enable_ip+0x98/0x2b0 kernel/softirq.c:268
local_bh_enable include/linux/bottom_half.h:33 [inline]
spin_unlock_bh include/linux/spinlock_rt.h:116 [inline]
ieee80211_ibss_work+0x344/0x10d0 net/mac80211/ibss.c:1656
cfg80211_wiphy_work+0x2cf/0x460 net/wireless/core.c:513
process_one_work kernel/workqueue.c:3302 [inline]
process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>

Tested on:

commit: 43cfbdda Merge tag 'for-linus-iommufd' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11621906580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4660d1ff2985517b
dashboard link: https://syzkaller.appspot.com/bug?extid=ecf51a7ccb6b1394e90c
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=1732d8ce580000