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

syzbot
2026-04-17T16:37:03Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in blk_update_request

==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
Read of size 1 at addr ffff888029ea23a8 by task syz-execprog/6206

CPU: 1 UID: 0 PID: 6206 Comm: syz-execprog 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
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
__kasan_check_byte+0x2a/0x40 mm/kasan/common.c:574
kasan_check_byte include/linux/kasan.h:402 [inline]
lock_acquire+0x84/0x350 kernel/locking/lockdep.c:5842
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
_raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
rtlock_slowlock kernel/locking/rtmutex.c:1910 [inline]
rtlock_lock kernel/locking/spinlock_rt.c:43 [inline]
__rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline]
rt_spin_lock+0x157/0x400 kernel/locking/spinlock_rt.c:57
spin_lock include/linux/spinlock_rt.h:45 [inline]
__wake_up_common_lock+0x2f/0x1e0 kernel/sched/wait.c:124
blk_update_request+0x57e/0xe60 block/blk-mq.c:1016
blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1178
blk_complete_reqs block/blk-mq.c:1253 [inline]
blk_done_softirq+0x10a/0x160 block/blk-mq.c:1258
handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
__local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302
lock_sock include/net/sock.h:1713 [inline]
tcp_recvmsg+0xdb/0x530 net/ipv4/tcp.c:2947
sock_recvmsg_nosec net/socket.c:1137 [inline]
sock_recvmsg+0xfa/0x1b0 net/socket.c:1159
sock_read_iter+0x25a/0x330 net/socket.c:1229
new_sync_read fs/read_write.c:493 [inline]
vfs_read+0x58b/0xa80 fs/read_write.c:574
ksys_read+0x156/0x270 fs/read_write.c:717
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: 0033:0x40d3ce
Code: ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 49 89 f2 48 89 fa 48 89 ce 48 89 df 0f 05 <48> 3d 01 f0 ff ff 76 15 48 f7 d8 48 89 c1 48 c7 c0 ff ff ff ff 48
RSP: 002b:00002b0cf6eef3d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 000000000040d3ce
RDX: 0000000001e71274 RSI: 00002b0cf7180000 RDI: 0000000000000006
RBP: 00002b0cf6eef418 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffed587ed60
R13: 0000000000000001 R14: 00002b0cf6d672c0 R15: 0000000000000001
</TASK>

Allocated by task 6803:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x3a6/0x690 mm/slub.c:5415
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
open_inline_log fs/jfs/jfs_logmgr.c:1157 [inline]
lmLogOpen+0x2d1/0xfa0 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

Freed by task 6544:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2689 [inline]
slab_free mm/slub.c:6246 [inline]
kfree+0x1c5/0x6c0 mm/slub.c:6561
lmLogClose+0x297/0x520 fs/jfs/jfs_logmgr.c:-1
jfs_umount+0x2fb/0x3d0 fs/jfs/jfs_umount.c:124
jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
generic_shutdown_super+0x13d/0x2d0 fs/super.c:646
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

The buggy address belongs to the object at ffff888029ea2000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 936 bytes inside of
freed 2048-byte region [ffff888029ea2000, ffff888029ea2800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888029ea1000 pfn:0x29ea0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000240(workingset|head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000240 ffff88801a01f000 ffffea0000e8dc10 ffffea0000cb5810
raw: ffff888029ea1000 0000000800080006 00000000f5000000 0000000000000000
head: 0080000000000240 ffff88801a01f000 ffffea0000e8dc10 ffffea0000cb5810
head: ffff888029ea1000 0000000800080006 00000000f5000000 0000000000000000
head: 0080000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3872, tgid 3872 (kworker/u8:15), ts 89329858437, free_ts 89297441219
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1860
prep_new_page mm/page_alloc.c:1868 [inline]
get_page_from_freelist+0x27c8/0x2840 mm/page_alloc.c:3948
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5228
alloc_slab_page mm/slub.c:3278 [inline]
allocate_slab+0x77/0x660 mm/slub.c:3467
new_slab mm/slub.c:3525 [inline]
refill_objects+0x33c/0x3d0 mm/slub.c:7251
refill_sheaf mm/slub.c:2816 [inline]
__pcs_replace_empty_main+0x373/0x720 mm/slub.c:4651
alloc_from_pcs mm/slub.c:4749 [inline]
slab_alloc_node mm/slub.c:4883 [inline]
__do_kmalloc_node mm/slub.c:5294 [inline]
__kmalloc_node_track_caller_noprof+0x60b/0x7e0 mm/slub.c:5403
kmalloc_reserve net/core/skbuff.c:635 [inline]
pskb_expand_head+0x230/0x1390 net/core/skbuff.c:2302
netlink_trim+0x1b3/0x2c0 net/netlink/af_netlink.c:1299
netlink_broadcast_filtered+0x80/0xea0 net/netlink/af_netlink.c:1512
nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
nlmsg_multicast include/net/netlink.h:1184 [inline]
nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2593
netif_state_change+0x297/0x3a0 net/core/dev.c:1605
__linkwatch_run_queue+0x575/0x850 net/core/link_watch.c:240
linkwatch_event+0x4c/0x60 net/core/link_watch.c:314
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
page last free pid 5861 tgid 5861 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1404 [inline]
__free_frozen_pages+0xfa6/0x10f0 mm/page_alloc.c:2945
__slab_free+0x252/0x2a0 mm/slub.c:5608
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4569 [inline]
slab_alloc_node mm/slub.c:4898 [inline]
kmem_cache_alloc_lru_noprof+0x33c/0x680 mm/slub.c:4917
sock_alloc_inode+0x2c/0x190 net/socket.c:328
alloc_inode+0x6a/0x1b0 fs/inode.c:345
new_inode_pseudo include/linux/fs.h:3022 [inline]
sock_alloc net/socket.c:697 [inline]
__sock_create+0x12d/0x9d0 net/socket.c:1628
sock_create net/socket.c:1722 [inline]
__sys_socket_create net/socket.c:1759 [inline]
__sys_socket+0xd6/0x1b0 net/socket.c:1806
__do_sys_socket net/socket.c:1820 [inline]
__se_sys_socket net/socket.c:1818 [inline]
__x64_sys_socket+0x7a/0x90 net/socket.c:1818
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

Memory state around the buggy address:
ffff888029ea2280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888029ea2300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888029ea2380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888029ea2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888029ea2480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: 43cfbdda Merge tag 'for-linus-iommufd' of git://git.ke..
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=16d3f036580000
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=11c4a4ce580000