KASAN: slab-use-after-free Write in jbd2_journal_commit_transaction

[Shuangpeng <shuangpeng.kernel@gmail.com>]

Hi Kernel Maintainers,

I hit the following KASAN report while testing current upstream kernel:

KASAN: slab-use-after-free in jbd2_journal_commit_transaction

on commit: bbeb83d3182abe0d245318e274e8531e5dd7a948 (Mar 24 2026)

The reproducer and .config files are here.
https://gist.github.com/shuangpengbai/032c84edf2505f7f74fb5757e1e6cd1d

The same reproducer sometimes also triggers a KASAN slab-out-of-bounds 
report at the same site, which may indicate the same underlying bug.

I’m happy to test debug patches or provide additional information.

Reported-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>

[   80.268862][ T8554] ==================================================================
[   80.269678][ T8554] BUG: KASAN: slab-use-after-free in jbd2_journal_commit_transaction (./include/linux/instrumented.h:97 ./include/asm-generic/bitops/instrumented-atomic.h:42 ./include/linux/jbd2.h:320 fs/jbd2/commit.c:828)
[   80.270623][ T8554] Write of size 8 at addr ffff8881687ee5e8 by task jbd2/loop0-4107/8554
[   80.271460][ T8554]
[   80.271710][ T8554] CPU: 1 UID: 0 PID: 8554 Comm: jbd2/loop0-4107 Not tainted 7.0.0-rc5-00051-gbbeb83d3182a #35 PR
[   80.271719][ T8554] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
[   80.271726][ T8554] Call Trace:
[   80.271729][ T8554]  <TASK>
[   80.271732][ T8554]  dump_stack_lvl (lib/dump_stack.c:122)
[   80.271743][ T8554]  print_report (mm/kasan/report.c:379 mm/kasan/report.c:482)
[   80.271795][ T8554]  kasan_report (mm/kasan/report.c:597)
[   80.271813][ T8554]  kasan_check_range (mm/kasan/generic.c:? mm/kasan/generic.c:200)
[   80.271821][ T8554]  jbd2_journal_commit_transaction (./include/linux/instrumented.h:97 ./include/asm-generic/bitops/instrumented-atomic.h:42 ./include/linux/jbd2.h:320 fs/jbd2/commit.c:828)
[   80.271912][ T8554]  kjournald2 (fs/jbd2/journal.c:202)
[   80.271974][ T8554]  kthread (kernel/kthread.c:437)
[   80.271986][ T8554]  ret_from_fork (arch/x86/kernel/process.c:164)
[   80.272022][ T8554]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
[   80.272034][ T8554]  </TASK>
[   80.272036][ T8554]
[   80.292650][ T8554] Freed by task 8373 on cpu 1 at 42.645081s:
[   80.293268][ T8554]  kasan_save_track (mm/kasan/common.c:58 mm/kasan/common.c:78)
[   80.293766][ T8554]  kasan_save_free_info (mm/kasan/generic.c:587)
[   80.294292][ T8554]  __kasan_slab_free (mm/kasan/common.c:287)
[   80.294796][ T8554]  kfree (mm/slub.c:6165 mm/slub.c:6483)
[   80.295206][ T8554]  tomoyo_realpath_from_path (security/tomoyo/realpath.c:287)
[   80.295789][ T8554]  tomoyo_realpath_nofollow (security/tomoyo/realpath.c:304)
[   80.296344][ T8554]  tomoyo_find_next_domain (security/tomoyo/domain.c:731)
[   80.296910][ T8554]  tomoyo_bprm_check_security (security/tomoyo/tomoyo.c:102)
[   80.297486][ T8554]  security_bprm_check (security/security.c:795)
[   80.298020][ T8554]  bprm_execve (fs/exec.c:1655 fs/exec.c:1696 fs/exec.c:1748)
[   80.298486][ T8554]  do_execveat_common (fs/exec.c:1846)
[   80.299019][ T8554]  __x64_sys_execve (fs/exec.c:1930 fs/exec.c:1924 fs/exec.c:1924)
[   80.299510][ T8554]  do_syscall_64 (arch/x86/entry/syscall_64.c:?)
[   80.299984][ T8554]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[   80.300597][ T8554]
[   80.300847][ T8554] The buggy address belongs to the object at ffff8881687ee000
[   80.300847][ T8554]  which belongs to the cache kmalloc-4k of size 4096
[   80.302261][ T8554] The buggy address is located 1512 bytes inside of
[   80.302261][ T8554]  freed 4096-byte region [ffff8881687ee000, ffff8881687ef000)
[   80.303678][ T8554]
[   80.303930][ T8554] The buggy address belongs to the physical page:
[   80.304590][ T8554] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1687e8
[   80.305499][ T8554] head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
[   80.306363][ T8554] flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
[   80.307153][ T8554] page_type: f5(slab)
[   80.307663][ T8554] raw: 017ff00000000040 ffff888100042140 dead000000000100 dead000000000122
[   80.308538][ T8554] raw: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
[   80.309414][ T8554] head: 017ff00000000040 ffff888100042140 dead000000000100 dead000000000122
[   80.310296][ T8554] head: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
[   80.311186][ T8554] head: 017ff00000000003 ffffea0005a1fa01 00000000ffffffff 00000000ffffffff
[   80.312076][ T8554] head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
[   80.312957][ T8554] page dumped because: kasan: bad access detected
[   80.313612][ T8554] page_owner tracks the page as allocated
[   80.314196][ T8554] page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN6
[   80.316275][ T8554]  post_alloc_hook (./include/linux/page_owner.h:? mm/page_alloc.c:1889)
[   80.316774][ T8554]  get_page_from_freelist (mm/page_alloc.c:? mm/page_alloc.c:3962)
[   80.317348][ T8554]  __alloc_frozen_pages_noprof (mm/page_alloc.c:5250)
[   80.317952][ T8554]  allocate_slab (mm/slub.c:3294 mm/slub.c:3481)
[   80.318430][ T8554]  refill_objects (mm/slub.c:7176)
[   80.318935][ T8554]  __pcs_replace_empty_main (mm/slub.c:? mm/slub.c:4615)
[   80.319510][ T8554]  __kmalloc_noprof (mm/slub.c:4718 mm/slub.c:4851 mm/slub.c:5259 mm/slub.c:5272)
[   80.320017][ T8554]  tomoyo_realpath_from_path (security/tomoyo/realpath.c:252)
[   80.320591][ T8554]  tomoyo_path_perm (security/tomoyo/file.c:151 security/tomoyo/file.c:827)
[   80.321100][ T8554]  security_inode_getattr (security/security.c:1870)
[   80.321648][ T8554]  __se_sys_newfstat (fs/stat.c:260 fs/stat.c:281 fs/stat.c:551 fs/stat.c:546)
[   80.322157][ T8554]  do_syscall_64 (arch/x86/entry/syscall_64.c:?)
[   80.322632][ T8554]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[   80.323246][ T8554] page last free pid 1 tgid 1 stack trace:
[   80.323852][ T8554]  __free_frozen_pages (./include/linux/page_owner.h:? mm/page_alloc.c:1433 mm/page_alloc.c:2978)
[   80.324384][ T8554]  free_contig_range (mm/page_alloc.c:7373)
[   80.324886][ T8554]  destroy_args (mm/debug_vm_pgtable.c:995)
[   80.325363][ T8554]  debug_vm_pgtable (mm/debug_vm_pgtable.c:?)
[   80.325870][ T8554]  do_one_initcall (init/main.c:?)
[   80.326370][ T8554]  do_initcall_level (init/main.c:1443)
[   80.326890][ T8554]  do_initcalls (init/main.c:1457)
[   80.327346][ T8554]  kernel_init_freeable (init/main.c:1696)
[   80.327888][ T8554]  kernel_init (init/main.c:1584)
[   80.328342][ T8554]  ret_from_fork (arch/x86/kernel/process.c:164)
[   80.328827][ T8554]  ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
[   80.329327][ T8554]
[   80.329577][ T8554] Memory state around the buggy address:
[   80.330154][ T8554]  ffff8881687ee480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   80.330981][ T8554]  ffff8881687ee500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   80.331803][ T8554] >ffff8881687ee580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   80.332625][ T8554]                                                           ^
[   80.333389][ T8554]  ffff8881687ee600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   80.334209][ T8554]  ffff8881687ee680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   80.335033][ T8554] ==================================================================


Best,
Shuangpeng