* Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone
2025-09-29 13:20 [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone syzbot
@ 2026-04-15 6:59 ` syzbot
2026-04-15 9:06 ` syzbot
` (3 subsequent siblings)
4 siblings, 0 replies; 11+ messages in thread
From: syzbot @ 2026-04-15 6:59 UTC (permalink / raw)
To: jfs-discussion, linux-kernel, shaggy, syzkaller-bugs
syzbot has found a reproducer for the following issue on:
HEAD commit: e6efabc0afca Add linux-next specific files for 20260414
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=161a18ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=56c2b36de3316f1b
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
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=107784ce580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e7099cbf73e4/disk-e6efabc0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/439c402df1b9/vmlinux-e6efabc0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc0c0175fc76/bzImage-e6efabc0.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/01761e564f3f/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=168401ba580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ecf51a7ccb6b1394e90c@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in lbmIODone+0x1312/0x16c0 fs/jfs/jfs_logmgr.c:2192
Read of size 4 at addr ffff888032de1208 by task ksoftirqd/1/31
CPU: 1 UID: 0 PID: 31 Comm: ksoftirqd/1 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
lbmIODone+0x1312/0x16c0 fs/jfs/jfs_logmgr.c:2192
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
run_ksoftirqd+0x52/0x180 kernel/softirq.c:1076
smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
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>
Allocated by task 6248:
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]
lbmLogInit fs/jfs/jfs_logmgr.c:1819 [inline]
lmLogInit+0x3e5/0x1a00 fs/jfs/jfs_logmgr.c:1267
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:4399 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4376
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 5959:
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
lbmLogShutdown fs/jfs/jfs_logmgr.c:1862 [inline]
lmLogShutdown+0x456/0x850 fs/jfs/jfs_logmgr.c:1681
lmLogClose+0x28a/0x520 fs/jfs/jfs_logmgr.c:1457
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 ffff888032de1200
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 8 bytes inside of
freed 256-byte region [ffff888032de1200, ffff888032de1300)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32de0
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88801a02cb40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88801a02cb40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5948, tgid 5948 (syz-executor), ts 136932809553, free_ts 131716582127
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
prep_new_page mm/page_alloc.c:1866 [inline]
get_page_from_freelist+0x27d6/0x2850 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
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_noprof+0x530/0x7b0 mm/slub.c:5307
kmalloc_noprof include/linux/slab.h:954 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
fib_create_info+0x1723/0x31f0 net/ipv4/fib_semantics.c:1400
fib_table_insert+0xc8/0x1b50 net/ipv4/fib_trie.c:1212
fib_magic+0x434/0x510 net/ipv4/fib_frontend.c:1134
fib_add_ifaddr+0x38d/0x5f0 net/ipv4/fib_frontend.c:1171
fib_netdev_event+0x382/0x490 net/ipv4/fib_frontend.c:1516
notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
call_netdevice_notifiers net/core/dev.c:2301 [inline]
__dev_notify_flags+0x1a9/0x310 net/core/dev.c:9849
netif_change_flags+0xe8/0x1a0 net/core/dev.c:9878
do_setlink+0xf82/0x4590 net/core/rtnetlink.c:3180
page last free pid 5958 tgid 5958 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1402 [inline]
__free_frozen_pages+0xf9b/0x10f0 mm/page_alloc.c:2943
__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_node_noprof+0x22a/0x6e0 mm/slub.c:4950
__alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702
alloc_skb include/linux/skbuff.h:1383 [inline]
nlmsg_new include/net/netlink.h:1055 [inline]
netlink_ack+0x146/0xa50 net/netlink/af_netlink.c:2487
netlink_rcv_skb+0x2b6/0x4b0 net/netlink/af_netlink.c:2556
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x780/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
__sys_sendto+0x67f/0x710 net/socket.c:2265
__do_sys_sendto net/socket.c:2272 [inline]
__se_sys_sendto net/socket.c:2268 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2268
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:
ffff888032de1100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888032de1180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888032de1200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888032de1280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888032de1300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone
2025-09-29 13:20 [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone syzbot
2026-04-15 6:59 ` syzbot
@ 2026-04-15 9:06 ` syzbot
2026-04-17 12:41 ` Edward Adam Davis
2026-04-17 14:20 ` Forwarded: [PATCH] jfs: fix use-after-free in lbmIODone by waiting for in-flight I/O syzbot
` (2 subsequent siblings)
4 siblings, 1 reply; 11+ messages in thread
From: syzbot @ 2026-04-15 9:06 UTC (permalink / raw)
To: jfs-discussion, linux-kernel, shaggy, syzkaller-bugs
syzbot has found a reproducer for the following issue on:
HEAD commit: e6efabc0afca Add linux-next specific files for 20260414
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17ee18ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=56c2b36de3316f1b
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
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11dc01ba580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173bfb02580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e7099cbf73e4/disk-e6efabc0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/439c402df1b9/vmlinux-e6efabc0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc0c0175fc76/bzImage-e6efabc0.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/81df22d6836d/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=107dfcd2580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ecf51a7ccb6b1394e90c@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in lbmIODone+0x1312/0x16c0 fs/jfs/jfs_logmgr.c:2192
Read of size 4 at addr ffff88802a45a608 by task ksoftirqd/1/31
CPU: 1 UID: 0 PID: 31 Comm: ksoftirqd/1 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
lbmIODone+0x1312/0x16c0 fs/jfs/jfs_logmgr.c:2192
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
run_ksoftirqd+0x52/0x180 kernel/softirq.c:1076
smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
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>
Allocated by task 6106:
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]
lbmLogInit fs/jfs/jfs_logmgr.c:1819 [inline]
lmLogInit+0x3e5/0x1a00 fs/jfs/jfs_logmgr.c:1267
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:4399 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4376
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 5969:
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
lbmLogShutdown fs/jfs/jfs_logmgr.c:1862 [inline]
lmLogShutdown+0x456/0x850 fs/jfs/jfs_logmgr.c:1681
lmLogClose+0x28a/0x520 fs/jfs/jfs_logmgr.c:1457
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 ffff88802a45a600
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 8 bytes inside of
freed 256-byte region [ffff88802a45a600, ffff88802a45a700)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2a45a
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88801a02cb40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88801a02cb40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 155, tgid 155 (kworker/u8:6), ts 12504727555, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
prep_new_page mm/page_alloc.c:1866 [inline]
get_page_from_freelist+0x27d6/0x2850 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
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]
__kmalloc_cache_noprof+0x44e/0x690 mm/slub.c:5410
kmalloc_noprof include/linux/slab.h:950 [inline]
scsi_probe_and_add_lun+0x2f8/0x48e0 drivers/scsi/scsi_scan.c:1225
__scsi_scan_target+0x1f0/0xe10 drivers/scsi/scsi_scan.c:1786
scsi_scan_channel drivers/scsi/scsi_scan.c:1874 [inline]
scsi_scan_host_selected+0x3d3/0x780 drivers/scsi/scsi_scan.c:1903
do_scsi_scan_host drivers/scsi/scsi_scan.c:2036 [inline]
do_scan_async+0x124/0x6f0 drivers/scsi/scsi_scan.c:2046
async_run_entry_fn+0xa8/0x440 kernel/async.c:129
process_one_work kernel/workqueue.c:3308 [inline]
process_scheduled_works+0xb68/0x1910 kernel/workqueue.c:3399
worker_thread+0xa90/0x1040 kernel/workqueue.c:3485
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
page_owner free stack trace missing
Memory state around the buggy address:
ffff88802a45a500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802a45a580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802a45a600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802a45a680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802a45a700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone
2026-04-15 9:06 ` syzbot
@ 2026-04-17 12:41 ` Edward Adam Davis
2026-04-17 12:59 ` syzbot
0 siblings, 1 reply; 11+ messages in thread
From: Edward Adam Davis @ 2026-04-17 12:41 UTC (permalink / raw)
To: syzbot+ecf51a7ccb6b1394e90c; +Cc: linux-kernel, syzkaller-bugs
#syz test: upstream master
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index 306165e61438..054cc01e4579 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -1984,7 +1984,7 @@ static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp)
submit_bio(bio);
}
- wait_event(bp->l_ioevent, (bp->l_flag != lbmREAD));
+ wait_event(bp->l_ioevent, (bp->l_flag == lbmDONE));
return 0;
}
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone
2026-04-17 12:41 ` Edward Adam Davis
@ 2026-04-17 12:59 ` syzbot
0 siblings, 0 replies; 11+ messages in thread
From: syzbot @ 2026-04-17 12:59 UTC (permalink / raw)
To: eadavis, linux-kernel, syzkaller-bugs
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
^ permalink raw reply [flat|nested] 11+ messages in thread
* Forwarded: [PATCH] jfs: fix use-after-free in lbmIODone by waiting for in-flight I/O
2025-09-29 13:20 [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone syzbot
2026-04-15 6:59 ` syzbot
2026-04-15 9:06 ` syzbot
@ 2026-04-17 14:20 ` syzbot
2026-04-17 16:22 ` Forwarded: Re: [syzbot] KASAN: slab-use-after-free Read in lbmIODone syzbot
2026-04-17 19:26 ` Forwarded: Re: [syzbot] [jfs?] " syzbot
4 siblings, 0 replies; 11+ messages in thread
From: syzbot @ 2026-04-17 14:20 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: [PATCH] jfs: fix use-after-free in lbmIODone by waiting for in-flight I/O
Author: tristmd@gmail.com
#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
From b8abd9772daa211b13c6db417c5c09495e688c61 Mon Sep 17 00:00:00 2001
From: Tristan Madani <tristan@talencesecurity.com>
Date: Fri, 17 Apr 2026 14:19:45 +0000
Subject: [PATCH] jfs: fix use-after-free in lbmIODone by waiting for in-flight
I/O
lbmLogShutdown() frees all log buffer heads from the freelist, but does
not wait for outstanding block I/O completions. When a log buffer write
is submitted via lbmStartIO() and the filesystem is unmounted before the
bio completes, lbmIODone() runs against a freed lbuf, causing a
use-after-free read.
Add an atomic I/O counter (io_count) to struct jfs_log. Increment it
in lbmStartIO() before submit_bio(), decrement it in lbmIODone() after
processing. In lbmLogShutdown(), wait for io_count to reach zero before
freeing buffer heads, ensuring no in-flight I/O references freed memory.
Reported-by: syzbot+ecf51a7ccb6b1394e90c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ecf51a7ccb6b1394e90c
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
fs/jfs/jfs_logmgr.c | 15 ++++++++++++++-
fs/jfs/jfs_logmgr.h | 3 +++
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index 306165e61..e309e1bbb 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -1805,6 +1805,9 @@ static int lbmLogInit(struct jfs_log * log)
*/
init_waitqueue_head(&log->free_wait);
+ atomic_set(&log->io_count, 0);
+ init_waitqueue_head(&log->io_wait);
+
log->lbuf_free = NULL;
for (i = 0; i < LOGPAGES;) {
@@ -1855,6 +1858,8 @@ static void lbmLogShutdown(struct jfs_log * log)
jfs_info("lbmLogShutdown: log:0x%p", log);
+ wait_event(log->io_wait, atomic_read(&log->io_count) == 0);
+
lbuf = log->lbuf_free;
while (lbuf) {
struct lbuf *next = lbuf->l_freelist;
@@ -2128,6 +2133,7 @@ static void lbmStartIO(struct lbuf * bp)
bio->bi_iter.bi_size = 0;
lbmIODone(bio);
} else {
+ atomic_inc(&log->io_count);
submit_bio(bio);
INCREMENT(lmStat.submitted);
}
@@ -2170,12 +2176,16 @@ static void lbmIODone(struct bio *bio)
struct lbuf *nextbp, *tail;
struct jfs_log *log;
unsigned long flags;
+ int is_write;
/*
* get back jfs buffer bound to the i/o buffer
*/
jfs_info("lbmIODone: bp:0x%p flag:0x%x", bp, bp->l_flag);
+ log = bp->l_log;
+ is_write = !(bp->l_flag & lbmREAD);
+
LCACHE_LOCK(flags); /* disable+lock */
if (bio->bi_status) {
@@ -2214,7 +2224,6 @@ static void lbmIODone(struct bio *bio)
INCREMENT(lmStat.pagedone);
/* update committed lsn */
- log = bp->l_log;
log->clsn = (bp->l_pn << L2LOGPSIZE) + bp->l_ceor;
if (bp->l_flag & lbmDIRECT) {
@@ -2299,6 +2308,10 @@ static void lbmIODone(struct bio *bio)
out:
bp->l_flag |= lbmDONE;
LCACHE_UNLOCK(flags);
+
+ if (is_write && !log->no_integrity)
+ if (atomic_dec_and_test(&log->io_count))
+ wake_up(&log->io_wait);
}
int jfsIOWait(void *arg)
diff --git a/fs/jfs/jfs_logmgr.h b/fs/jfs/jfs_logmgr.h
index 09e0ef6ae..50388562b 100644
--- a/fs/jfs/jfs_logmgr.h
+++ b/fs/jfs/jfs_logmgr.h
@@ -400,6 +400,9 @@ struct jfs_log {
uuid_t uuid; /* 16: 128-bit uuid of log device */
int no_integrity; /* 3: flag to disable journaling to disk */
+
+ atomic_t io_count; /* outstanding I/O count */
+ wait_queue_head_t io_wait; /* wait for all I/O to complete */
};
/*
--
2.47.3
^ permalink raw reply related [flat|nested] 11+ messages in thread* Forwarded: Re: [syzbot] KASAN: slab-use-after-free Read in lbmIODone
2025-09-29 13:20 [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone syzbot
` (2 preceding siblings ...)
2026-04-17 14:20 ` Forwarded: [PATCH] jfs: fix use-after-free in lbmIODone by waiting for in-flight I/O syzbot
@ 2026-04-17 16:22 ` syzbot
2026-04-17 19:26 ` Forwarded: Re: [syzbot] [jfs?] " syzbot
4 siblings, 0 replies; 11+ messages in thread
From: syzbot @ 2026-04-17 16:22 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [syzbot] KASAN: slab-use-after-free Read in lbmIODone
Author: tristmd@gmail.com
#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>From 9fd2228641cd56d9e735211ce0d2decfd03aaaa9 Mon Sep 17 00:00:00 2001
From: Tristan Madani <tristan@talencesecurity.com>
Date: Fri, 17 Apr 2026 16:15:16 +0000
Subject: [PATCH] jfs: fix use-after-free in lbmIODone by waiting for in-flight
I/O
lbmLogShutdown() frees all log buffer heads without waiting for
outstanding block I/O completions. When a write bio submitted via
lbmStartIO() completes after the buffers are freed, lbmIODone()
dereferences the freed struct lbuf via bio->bi_private.
Add an atomic io_count and wait_queue_head_t to struct jfs_log.
Increment before submit_bio(), decrement after processing in
lbmIODone(), and wait in lbmLogShutdown() for io_count == 0
before freeing.
Reported-by: syzbot+ecf51a7ccb6b1394e90c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ecf51a7ccb6b1394e90c
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
fs/jfs/jfs_logmgr.c | 15 ++++++++++++++-
fs/jfs/jfs_logmgr.h | 3 +++
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index 306165e..e309e1b 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -1805,6 +1805,9 @@ static int lbmLogInit(struct jfs_log * log)
*/
init_waitqueue_head(&log->free_wait);
+ atomic_set(&log->io_count, 0);
+ init_waitqueue_head(&log->io_wait);
+
log->lbuf_free = NULL;
for (i = 0; i < LOGPAGES;) {
@@ -1855,6 +1858,8 @@ static void lbmLogShutdown(struct jfs_log * log)
jfs_info("lbmLogShutdown: log:0x%p", log);
+ wait_event(log->io_wait, atomic_read(&log->io_count) == 0);
+
lbuf = log->lbuf_free;
while (lbuf) {
struct lbuf *next = lbuf->l_freelist;
@@ -2128,6 +2133,7 @@ static void lbmStartIO(struct lbuf * bp)
bio->bi_iter.bi_size = 0;
lbmIODone(bio);
} else {
+ atomic_inc(&log->io_count);
submit_bio(bio);
INCREMENT(lmStat.submitted);
}
@@ -2170,12 +2176,16 @@ static void lbmIODone(struct bio *bio)
struct lbuf *nextbp, *tail;
struct jfs_log *log;
unsigned long flags;
+ int is_write;
/*
* get back jfs buffer bound to the i/o buffer
*/
jfs_info("lbmIODone: bp:0x%p flag:0x%x", bp, bp->l_flag);
+ log = bp->l_log;
+ is_write = !(bp->l_flag & lbmREAD);
+
LCACHE_LOCK(flags); /* disable+lock */
if (bio->bi_status) {
@@ -2214,7 +2224,6 @@ static void lbmIODone(struct bio *bio)
INCREMENT(lmStat.pagedone);
/* update committed lsn */
- log = bp->l_log;
log->clsn = (bp->l_pn << L2LOGPSIZE) + bp->l_ceor;
if (bp->l_flag & lbmDIRECT) {
@@ -2299,6 +2308,10 @@ static void lbmIODone(struct bio *bio)
out:
bp->l_flag |= lbmDONE;
LCACHE_UNLOCK(flags);
+
+ if (is_write && !log->no_integrity)
+ if (atomic_dec_and_test(&log->io_count))
+ wake_up(&log->io_wait);
}
int jfsIOWait(void *arg)
diff --git a/fs/jfs/jfs_logmgr.h b/fs/jfs/jfs_logmgr.h
index 09e0ef6..6fa7d9f 100644
--- a/fs/jfs/jfs_logmgr.h
+++ b/fs/jfs/jfs_logmgr.h
@@ -400,6 +400,9 @@ struct jfs_log {
uuid_t uuid; /* 16: 128-bit uuid of log device */
int no_integrity; /* 3: flag to disable journaling to disk */
+
+ atomic_t io_count; /* outstanding I/O count */
+ wait_queue_head_t io_wait; /* wait for all I/O to complete */
};
/*
--
2.47.3
^ permalink raw reply related [flat|nested] 11+ messages in thread* Forwarded: Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone
2025-09-29 13:20 [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone syzbot
` (3 preceding siblings ...)
2026-04-17 16:22 ` Forwarded: Re: [syzbot] KASAN: slab-use-after-free Read in lbmIODone syzbot
@ 2026-04-17 19:26 ` syzbot
4 siblings, 0 replies; 11+ messages in thread
From: syzbot @ 2026-04-17 19:26 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone
Author: tristmd@gmail.com
#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index XXXXXXX..XXXXXXX 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -1805,6 +1805,8 @@ static int lbmLogInit(struct jfs_log * log)
*/
init_waitqueue_head(&log->free_wait);
+ atomic_set(&log->io_count, 0);
+
log->lbuf_free = NULL;
for (i = 0; i < LOGPAGES;) {
@@ -1855,6 +1857,8 @@ static void lbmLogShutdown(struct jfs_log * log)
jfs_info("lbmLogShutdown: log:0x%p", log);
+ wait_var_event(&log->io_count, atomic_read(&log->io_count) == 0);
+
lbuf = log->lbuf_free;
while (lbuf) {
struct lbuf *next = lbuf->l_freelist;
@@ -2128,6 +2132,7 @@ static void lbmStartIO(struct lbuf * bp)
bio->bi_iter.bi_size = 0;
lbmIODone(bio);
} else {
+ atomic_inc(&log->io_count);
submit_bio(bio);
INCREMENT(lmStat.submitted);
}
@@ -2170,12 +2175,16 @@ static void lbmIODone(struct bio *bio)
struct lbuf *nextbp, *tail;
struct jfs_log *log;
unsigned long flags;
+ int is_write;
/*
* get back jfs buffer bound to the i/o buffer
*/
jfs_info("lbmIODone: bp:0x%p flag:0x%x", bp, bp->l_flag);
+ log = bp->l_log;
+ is_write = !(bp->l_flag & lbmREAD);
+
LCACHE_LOCK(flags); /* disable+lock */
if (bio->bi_status) {
@@ -2214,7 +2223,6 @@ static void lbmIODone(struct bio *bio)
INCREMENT(lmStat.pagedone);
/* update committed lsn */
- log = bp->l_log;
log->clsn = (bp->l_pn << L2LOGPSIZE) + bp->l_ceor;
if (bp->l_flag & lbmDIRECT) {
@@ -2299,6 +2307,10 @@ static void lbmIODone(struct bio *bio)
out:
bp->l_flag |= lbmDONE;
LCACHE_UNLOCK(flags);
+
+ if (is_write && !log->no_integrity)
+ if (atomic_dec_and_test(&log->io_count))
+ wake_up_var(&log->io_count);
}
int jfsIOWait(void *arg)
diff --git a/fs/jfs/jfs_logmgr.h b/fs/jfs/jfs_logmgr.h
index XXXXXXX..XXXXXXX 100644
--- a/fs/jfs/jfs_logmgr.h
+++ b/fs/jfs/jfs_logmgr.h
@@ -400,6 +400,8 @@ struct jfs_log {
uuid_t uuid; /* 16: 128-bit uuid of log device */
int no_integrity; /* 3: flag to disable journaling to disk */
+
+ atomic_t io_count; /* outstanding I/O count for shutdown drain */
};
/*
^ permalink raw reply [flat|nested] 11+ messages in thread