syzbot


KASAN: slab-use-after-free Read in txLazyUnlock (2)

Status: moderation: reported on 2025/08/23 11:03
Subsystems: jfs
[Documentation on labels]
Reported-by: syzbot+27ba3d071a1b7cd537ef@syzkaller.appspotmail.com
First crash: 10d, last: 10d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in txLazyUnlock jfs 19 1 239d 235d 0/29 auto-obsoleted due to no activity on 2025/04/01 16:48

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in JFS_SBI fs/jfs/jfs_incore.h:217 [inline]
BUG: KASAN: slab-use-after-free in txLazyUnlock+0xf6/0x190 fs/jfs/jfs_txnmgr.c:2784
Read of size 8 at addr ffff888059de07a0 by task syz-executor/9721

CPU: 1 UID: 0 PID: 9721 Comm: syz-executor Tainted: G        W           6.17.0-rc2-syzkaller-00028-gbe48bcf004f9 #0 PREEMPT_{RT,(full)} [  425.005583][ T9721] CPU: 1 UID: 0 PID: 9721 Comm: syz-executor Tainted: G        W           6.17.0-rc2-syzkaller-00028-gbe48bcf004f9 #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 JFS_SBI fs/jfs/jfs_incore.h:217 [inline]
 txLazyUnlock+0xf6/0x190 fs/jfs/jfs_txnmgr.c:2784
 lmPostGC fs/jfs/jfs_logmgr.c:845 [inline]
 lbmIODone+0x91d/0x1640 fs/jfs/jfs_logmgr.c:2293
 lbmWrite+0x34e/0x4a0 fs/jfs/jfs_logmgr.c:2067
 lmGCwrite fs/jfs/jfs_logmgr.c:-1 [inline]
 jfs_flush_journal+0x538/0xed0 fs/jfs/jfs_logmgr.c:1548
 jfs_umount+0x178/0x3c0 fs/jfs/jfs_umount.c:58
 jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x132/0x2c0 fs/super.c:643
 kill_block_super+0x44/0x90 fs/super.c:1766
 deactivate_locked_super+0xbc/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1378
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8832b1ff17
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffed7cfa708 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f8832ba1c05 RCX: 00007f8832b1ff17
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffed7cfa7c0
RBP: 00007ffed7cfa7c0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffed7cfb850
R13: 00007f8832ba1c05 R14: 00000000000679c6 R15: 00007ffed7cfb890
 </TASK>

Allocated by task 8547:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4365 [inline]
 __kmalloc_node_track_caller_noprof+0x1f3/0x450 mm/slub.c:4384
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:600
 __alloc_skb+0x142/0x2d0 net/core/skbuff.c:669
 alloc_skb include/linux/skbuff.h:1336 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:763 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:820 [inline]
 nsim_dev_trap_report_work+0x29f/0xbc0 drivers/net/netdevsim/dev.c:866
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 8547:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2417 [inline]
 slab_free mm/slub.c:4680 [inline]
 kfree+0x195/0x550 mm/slub.c:4879
 skb_release_data+0x62d/0x7c0 net/core/skbuff.c:1086
 skb_release_all net/core/skbuff.c:1151 [inline]
 __kfree_skb net/core/skbuff.c:1165 [inline]
 consume_skb+0x9e/0xf0 net/core/skbuff.c:1397
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:836 [inline]
 nsim_dev_trap_report_work+0x7fa/0xbc0 drivers/net/netdevsim/dev.c:866
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888059de0000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1952 bytes inside of
 freed 4096-byte region [ffff888059de0000, ffff888059de1000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x59de0
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 ffff888019842140 ffffea000156d000 dead000000000002
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 0080000000000040 ffff888019842140 ffffea000156d000 dead000000000002
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 0080000000000003 ffffea0001677801 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 10440, tgid 10440 (udevadm), ts 377209770629, free_ts 371404324216
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x2119/0x21b0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2487 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2655
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0x8d1/0xdd0 mm/slub.c:3891
 __slab_alloc mm/slub.c:3981 [inline]
 __slab_alloc_node mm/slub.c:4056 [inline]
 slab_alloc_node mm/slub.c:4217 [inline]
 __kmalloc_cache_noprof+0xe6/0x320 mm/slub.c:4391
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 uevent_show+0x15a/0x310 drivers/base/core.c:2751
 dev_attr_show+0x55/0xc0 drivers/base/core.c:2421
 sysfs_kf_seq_show+0x310/0x490 fs/sysfs/file.c:65
 seq_read_iter+0x4e8/0xe10 fs/seq_file.c:230
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x560/0xa30 fs/read_write.c:572
 ksys_read+0x14b/0x260 fs/read_write.c:715
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 8417 tgid 8417 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xb59/0xce0 mm/page_alloc.c:2895
 discard_slab mm/slub.c:2753 [inline]
 __put_partials+0x159/0x1a0 mm/slub.c:3218
 __slab_free+0x2b3/0x390 mm/slub.c:4550
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:340
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4180 [inline]
 slab_alloc_node mm/slub.c:4229 [inline]
 kmem_cache_alloc_lru_noprof+0x14c/0x310 mm/slub.c:4248
 shmem_alloc_inode+0x28/0x40 mm/shmem.c:5211
 alloc_inode+0x6a/0x1b0 fs/inode.c:346
 new_inode+0x22/0x170 fs/inode.c:1145
 __shmem_get_inode mm/shmem.c:3110 [inline]
 shmem_get_inode+0x346/0xe00 mm/shmem.c:3184
 shmem_mknod+0x18c/0x3e0 mm/shmem.c:3905
 lookup_open fs/namei.c:3708 [inline]
 open_last_lookups fs/namei.c:3807 [inline]
 path_openat+0x14fd/0x3840 fs/namei.c:4043
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1461

Memory state around the buggy address:
 ffff888059de0680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888059de0700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888059de0780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888059de0800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888059de0880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/19 10:59 upstream be48bcf004f9 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in txLazyUnlock
* Struck through repros no longer work on HEAD.