KASAN: slab-use-after-free Read in lmLog

Status: upstream: reported on 2026/08/04 01:44
Subsystems: jfs
Labels: prio:normal actionable
[Documentation on labels]
Reported-by: syzbot+5e630048345c54c4d7f4@syzkaller.appspotmail.com
First crash: 100d, last: 4d11h
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
c8d86e21 repro-c Reproduced: ✅ ❓ KASAN: slab-use-after-free Read in lmLog 2026/08/05 15:00 2026/08/05 15:00 2026/08/05 19:28 e33390b8
5ba37477 moderation Actionable: ✅ ❓ KASAN: slab-use-after-free Read in lmLog 2026/08/04 01:06 2026/08/04 01:06 2026/08/04 01:44 cb1adeae
07e49de8 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in lmLog 2026/08/01 01:58 2026/08/01 01:58 2026/08/01 02:35 7664cf44
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [jfs?] KASAN: slab-use-after-free Read in lmLog 0 (1) 2026/08/04 01:44
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/06 07:08 20m glider@google.com upstream report log

Sample crash report:
add_index: next_index = 0.  Resetting!
==================================================================
BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline]
BUG: KASAN: slab-use-after-free in mutex_lock_nested+0x55/0x1d0 kernel/locking/rtmutex_api.c:580
Read of size 1 at addr ffff88806401f950 by task syz.7.101/6858

CPU: 1 UID: 0 PID: 6858 Comm: syz.7.101 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
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:585
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire+0x7d/0x350 kernel/locking/lockdep.c:5916
 __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline]
 mutex_lock_nested+0x55/0x1d0 kernel/locking/rtmutex_api.c:580
 lmLog+0x78/0xa10 fs/jfs/jfs_logmgr.c:234
 dtLog fs/jfs/jfs_txnmgr.c:1620 [inline]
 txLog fs/jfs/jfs_txnmgr.c:1402 [inline]
 txCommit+0x1c92/0x54a0 fs/jfs/jfs_txnmgr.c:1266
 add_missing_indices+0x7e5/0xb30 fs/jfs/jfs_dtree.c:2671
 jfs_readdir+0x1d15/0x33f0 fs/jfs/jfs_dtree.c:3028
 wrap_directory_iterator+0x99/0xe0 fs/readdir.c:67
 iterate_dir+0x3ea/0x8a0 fs/readdir.c:114
 __do_sys_getdents64 fs/readdir.c:404 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:389
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc6d92cfb19
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc6d74fd028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fc6d9556090 RCX: 00007fc6d92cfb19
RDX: 00000000000000e0 RSI: 0000200000000d00 RDI: 0000000000000004
RBP: 00007fc6d9367af8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc6d9556128 R14: 00007fc6d9556090 R15: 00007ffe1ae7e038
 </TASK>

Allocated by task 6847:
 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:409 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:426
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x3d0/0x670 mm/slub.c:5680
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 open_inline_log fs/jfs/jfs_logmgr.c:1157 [inline]
 lmLogOpen+0x2d1/0xf90 fs/jfs/jfs_logmgr.c:1067
 jfs_mount_rw+0xf3/0x670 fs/jfs/jfs_mount.c:257
 jfs_fill_super+0x769/0xda0 fs/jfs/super.c:533
 get_tree_bdev_flags+0x436/0x500 fs/super.c:1821
 vfs_get_tree+0x92/0x2a0 fs/super.c:1881
 fc_mount fs/namespace.c:1282 [inline]
 do_new_mount_fc fs/namespace.c:3910 [inline]
 do_new_mount+0x325/0xb00 fs/namespace.c:3986
 do_mount fs/namespace.c:4350 [inline]
 __do_sys_mount fs/namespace.c:4565 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4542
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6847:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:264 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2780 [inline]
 slab_free mm/slub.c:6630 [inline]
 kfree+0x1c5/0x6d0 mm/slub.c:6923
 lmLogClose+0x296/0x530 fs/jfs/jfs_logmgr.c:-1
 jfs_reconfigure+0x6d3/0x990 fs/jfs/super.c:421
 reconfigure_super+0x232/0x8f0 fs/super.c:1097
 do_remount fs/namespace.c:3538 [inline]
 path_mount+0xd51/0x1050 fs/namespace.c:4329
 do_mount fs/namespace.c:4350 [inline]
 __do_sys_mount fs/namespace.c:4565 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4542
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88806401f800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 336 bytes inside of
 freed 1024-byte region [ffff88806401f800, ffff88806401fc00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x64018
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88813ff13dc0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88813ff13dc0 dead000000000100 dead000000000122
head: 0000000000000000 0000000000100010 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 48, tgid 48 (kworker/u8:2), ts 103899060895
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1856
 prep_new_page mm/page_alloc.c:1864 [inline]
 get_page_from_freelist+0x258b/0x2600 mm/page_alloc.c:3935
 __alloc_frozen_pages_noprof+0x227/0x440 mm/page_alloc.c:5444
 alloc_slab_page mm/slub.c:3384 [inline]
 allocate_slab+0x7d/0x5e0 mm/slub.c:3499
 new_slab mm/slub.c:3550 [inline]
 refill_objects+0x2d8/0x350 mm/slub.c:7539
 refill_sheaf mm/slub.c:2917 [inline]
 __pcs_replace_empty_main+0x339/0x690 mm/slub.c:4811
 alloc_from_pcs mm/slub.c:4887 [inline]
 slab_alloc_node mm/slub.c:5021 [inline]
 __do_kmalloc_node mm/slub.c:5530 [inline]
 __kmalloc_noprof+0x546/0x790 mm/slub.c:5556
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 ieee802_11_parse_elems_full+0x14b/0x2a10 net/mac80211/parse.c:1077
 ieee80211_inform_bss+0x1b3/0x1150 net/mac80211/scan.c:91
 rdev_inform_bss net/wireless/rdev-ops.h:457 [inline]
 cfg80211_inform_single_bss_data+0xd98/0x1bf0 net/wireless/scan.c:2447
 cfg80211_inform_bss_data+0x25b/0x3be0 net/wireless/scan.c:3303
 cfg80211_inform_bss_frame_data+0x51a/0xae0 net/wireless/scan.c:3399
 ieee80211_bss_info_update+0x772/0xa30 net/mac80211/scan.c:236
 ieee80211_rx_bss_info net/mac80211/ibss.c:1065 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1546 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x1ce1/0x2c40 net/mac80211/ibss.c:1573
 ieee80211_iface_process_skb net/mac80211/iface.c:1805 [inline]
 ieee80211_iface_work+0x769/0xfa0 net/mac80211/iface.c:1859
 cfg80211_wiphy_work+0x29e/0x420 net/wireless/core.c:610
page last free pid 5909 tgid 5909 ts 103661168697 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1403 [inline]
 __free_frozen_pages+0xf8a/0x1060 mm/page_alloc.c:2954
 __slab_free+0x26e/0x2c0 mm/slub.c:5926
 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:361
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4720 [inline]
 slab_alloc_node mm/slub.c:5033 [inline]
 kmem_cache_alloc_node_noprof+0x3f7/0x660 mm/slub.c:5105
 __alloc_skb+0x1db/0x7a0 net/core/skbuff.c:705
 netlink_sendmsg+0x5cd/0xb20 net/netlink/af_netlink.c:1895
 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800
 __sock_sendmsg net/socket.c:818 [inline]
 __sys_sendto+0x41e/0x5d0 net/socket.c:2283
 __do_sys_sendto net/socket.c:2290 [inline]
 __se_sys_sendto net/socket.c:2286 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2286
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88806401f800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806401f880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88806401f900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff88806401f980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806401fa00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/03 03:59 upstream 6628e7d4c6b2 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in lmLog
2026/09/29 20:04 upstream 6f8319e3e9a4 328436b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in lmLog
2026/08/22 05:29 upstream 818bebeb63dd 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in lmLog
2026/07/30 05:59 upstream fc46aed51f62 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in lmLog
* Struck through repros no longer work on HEAD.