syzbot


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

Status: upstream: reported C repro on 2025/06/21 09:40
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+1473770ca06b052afcaa@syzkaller.appspotmail.com
First crash: 275d, last: 6d12h
Bug presence (1)
Date Name Commit Repro Result
2025/06/29 upstream (ToT) dfba48a70cb6 C [report] general protection fault in lmLogSync
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in jfs_syncpt jfs 19 C inconclusive 1215 9h41m 776d 0/29 upstream: reported C repro on 2024/02/07 09:29
linux-5.15 KASAN: use-after-free Read in jfs_syncpt origin:upstream 19 C 152 13d 769d 0/3 upstream: reported C repro on 2024/02/13 19:07
linux-6.1 KASAN: use-after-free Read in jfs_syncpt origin:upstream 19 C error 165 28d 710d 0/3 upstream: reported C repro on 2024/04/12 18:15
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2025/12/25 00:02 2h07m bisect fix linux-6.6.y OK (0) job log log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __mutex_waiter_is_first kernel/locking/mutex.c:197 [inline]
BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/mutex.c:681 [inline]
BUG: KASAN: slab-use-after-free in __mutex_lock+0x6c2/0xcc0 kernel/locking/mutex.c:747
Read of size 8 at addr ffff88802d20d108 by task jfsCommit/112

CPU: 0 PID: 112 Comm: jfsCommit Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 __mutex_waiter_is_first kernel/locking/mutex.c:197 [inline]
 __mutex_lock_common kernel/locking/mutex.c:681 [inline]
 __mutex_lock+0x6c2/0xcc0 kernel/locking/mutex.c:747
 jfs_syncpt+0x25/0x90 fs/jfs/jfs_logmgr.c:1039
 txEnd+0x2e5/0x520 fs/jfs/jfs_txnmgr.c:550
 txLazyCommit fs/jfs/jfs_txnmgr.c:2685 [inline]
 jfs_lazycommit+0x5a4/0xa70 fs/jfs/jfs_txnmgr.c:2733
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Allocated by task 5958:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 open_inline_log fs/jfs/jfs_logmgr.c:1159 [inline]
 lmLogOpen+0x2df/0xfb0 fs/jfs/jfs_logmgr.c:1069
 jfs_mount_rw+0xef/0x670 fs/jfs/jfs_mount.c:257
 jfs_fill_super+0x598/0xad0 fs/jfs/super.c:565
 mount_bdev+0x221/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 5880:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1811 [inline]
 slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1e0 mm/slub.c:3843
 lmLogClose+0x297/0x520 fs/jfs/jfs_logmgr.c:-1
 jfs_umount+0x2ef/0x3c0 fs/jfs/jfs_umount.c:114
 jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x134/0x2b0 fs/super.c:693
 kill_block_super+0x44/0x90 fs/super.c:1660
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x43b/0x4d0 fs/namespace.c:1259
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88802d20d000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 264 bytes inside of
 freed 1024-byte region [ffff88802d20d000, ffff88802d20d400)

The buggy address belongs to the physical page:
page:ffffea0000b48200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2d208
head:ffffea0000b48200 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017c41dc0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5805, tgid 5805 (syz-executor), ts 84230014322, free_ts 84223943142
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581
 prep_new_page mm/page_alloc.c:1588 [inline]
 get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4486
 alloc_slab_page+0x5d/0x160 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x19e/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa4/0x230 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 ipt_alloc_initial_table+0x6e/0x610 net/ipv4/netfilter/ip_tables.c:36
 iptable_filter_table_init+0x1c/0xb0 net/ipv4/netfilter/iptable_filter.c:42
 xt_find_table_lock+0x306/0x3e0 net/netfilter/x_tables.c:1259
 xt_request_find_table_lock+0x26/0x100 net/netfilter/x_tables.c:1284
 get_info net/ipv4/netfilter/ip_tables.c:963 [inline]
 do_ipt_get_ctl+0x717/0x1200 net/ipv4/netfilter/ip_tables.c:1659
 nf_getsockopt+0x262/0x280 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x19f/0x230 net/ipv4/ip_sockglue.c:1790
 do_sock_getsockopt+0x379/0x450 net/socket.c:2383
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1181 [inline]
 free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2458
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x11a/0x2d0 mm/slub.c:3519
 getname_kernel+0x5a/0x2f0 fs/namei.c:228
 kern_path+0x1d/0x50 fs/namei.c:2617
 do_loopback+0xce/0x500 fs/namespace.c:2643
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88802d20d000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802d20d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802d20d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88802d20d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802d20d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (32):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/01 12:20 linux-6.6.y 7a137e9bfa0e 43249bac .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/09/30 08:59 linux-6.6.y 147338df3487 86341da6 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/08/18 03:52 linux-6.6.y bb9c90ab9c5a 1804e95e .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/06/22 06:37 linux-6.6.y 6282921b6825 d6cdfb8a .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/08/23 01:11 linux-6.6.y bb9c90ab9c5a bf27483f .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/03/17 20:59 linux-6.6.y 4fc00fe35d46 c8810548 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/03/01 19:35 linux-6.6.y 7a137e9bfa0e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/03/01 02:03 linux-6.6.y 7a137e9bfa0e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/02/25 17:48 linux-6.6.y 7a137e9bfa0e 94a9671e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/02/21 12:40 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/02/10 01:30 linux-6.6.y c56aaf1a85ae 4ab09a02 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/02/09 07:36 linux-6.6.y c56aaf1a85ae 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/01/14 14:27 linux-6.6.y c596736dadab d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2026/01/11 16:29 linux-6.6.y c596736dadab d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/12/25 02:22 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/11/20 13:07 linux-6.6.y 0a805b6ea8cd 2cc4c24a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/11/17 12:28 linux-6.6.y 0a805b6ea8cd ef766cd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/10/13 12:26 linux-6.6.y 655054d2c3c1 b6605ba8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/10/10 01:58 linux-6.6.y e617101e5626 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/10/09 11:34 linux-6.6.y e617101e5626 7e2882b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/09/24 05:30 linux-6.6.y af1544b5d072 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/09/19 08:34 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/09/11 23:02 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/08/28 20:09 linux-6.6.y cc1a1c5b404a d401b9d7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/08/24 22:13 linux-6.6.y bb9c90ab9c5a bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/08/09 22:31 linux-6.6.y 3a8ababb8b6a 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/07/18 22:19 linux-6.6.y d96eb99e2f0e 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/07/14 06:07 linux-6.6.y 59a2de10b81a 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/07/05 09:31 linux-6.6.y 3f5b4c104b7d 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/07/03 19:02 linux-6.6.y 3f5b4c104b7d 115ceea7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/06/27 12:50 linux-6.6.y 3f5b4c104b7d 803ce19b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
2025/06/21 09:39 linux-6.6.y 6282921b6825 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in jfs_syncpt
* Struck through repros no longer work on HEAD.