From: syzbot <syzbot+ea7ed3bb2f444cb4dfeb@syzkaller.appspotmail.com>
To: jfs-discussion@lists.sourceforge.net, jie.wang@intel.com,
linux-kernel@vger.kernel.org, shaggy@kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [jfs?] KASAN: slab-use-after-free Write in lmLogSync
Date: Thu, 25 Jun 2026 12:01:28 -0700 [thread overview]
Message-ID: <6a3d7b08.80e5668d.5d0ef.0006.GAE@google.com> (raw)
In-Reply-To: <6a1eb319.c1435f33.112120.0156.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: ab9de95c9cf9 Merge tag 'rust-7.2-2' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e27046580000
kernel config: https://syzkaller.appspot.com/x/.config?x=86ba763b42fa66a
dashboard link: https://syzkaller.appspot.com/bug?extid=ea7ed3bb2f444cb4dfeb
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=109b430e580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c16df342a923/disk-ab9de95c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ddf00a828178/vmlinux-ab9de95c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f468c716a7be/bzImage-ab9de95c.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/410234fc5bd7/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=13bc540a580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ea7ed3bb2f444cb4dfeb@syzkaller.appspotmail.com
... Log Wrap ... Log Wrap ... Log Wrap ...
==================================================================
BUG: KASAN: slab-use-after-free in lmLogSync+0x9a5/0xa40 fs/jfs/jfs_logmgr.c:1003
Write of size 4 at addr ffff888078b39a18 by task jfsCommit/119
CPU: 1 UID: 0 PID: 119 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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
lmLogSync+0x9a5/0xa40 fs/jfs/jfs_logmgr.c:1003
jfs_syncpt+0x7b/0x90 fs/jfs/jfs_logmgr.c:1039
txEnd+0x2e5/0x530 fs/jfs/jfs_txnmgr.c:551
txLazyCommit fs/jfs/jfs_txnmgr.c:2686 [inline]
jfs_lazycommit+0x5d6/0xac0 fs/jfs/jfs_txnmgr.c:2735
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 6176:
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+0x32d/0x660 mm/slub.c:5515
_kmalloc_noprof include/linux/slab.h:969 [inline]
_kzalloc_noprof include/linux/slab.h:1290 [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+0x430/0x4f0 fs/super.c:1634
vfs_get_tree+0x92/0x2a0 fs/super.c:1694
fc_mount fs/namespace.c:1198 [inline]
do_new_mount_fc fs/namespace.c:3765 [inline]
do_new_mount+0x319/0xdc0 fs/namespace.c:3841
do_mount fs/namespace.c:4174 [inline]
__do_sys_mount fs/namespace.c:4390 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4367
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 5770:
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: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:2705 [inline]
slab_free mm/slub.c:6405 [inline]
kfree+0x1c5/0x640 mm/slub.c:6720
lmLogClose+0x296/0x530 fs/jfs/jfs_logmgr.c:-1
jfs_umount+0x2da/0x3b0 fs/jfs/jfs_umount.c:124
jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
generic_shutdown_super+0x13d/0x2d0 fs/super.c:647
kill_block_super+0x44/0x90 fs/super.c:1665
deactivate_locked_super+0xbc/0x130 fs/super.c:477
cleanup_mnt+0x3d3/0x460 fs/namespace.c:1317
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:70 [inline]
exit_to_user_mode_loop+0x1fa/0x730 kernel/entry/common.c:101
__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:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888078b39800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 536 bytes inside of
freed 1024-byte region [ffff888078b39800, ffff888078b39c00)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x78b38
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813fe25dc0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe25dc0 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 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 6055, tgid 6055 (kworker/u8:2), ts 107606662230, free_ts 107579789139
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3294 [inline]
allocate_slab+0x79/0x5e0 mm/slub.c:3408
new_slab mm/slub.c:3454 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7338
refill_sheaf mm/slub.c:2832 [inline]
__pcs_replace_empty_main+0x2bf/0x6b0 mm/slub.c:4703
alloc_from_pcs mm/slub.c:4801 [inline]
slab_alloc_node mm/slub.c:4933 [inline]
__do_kmalloc_node mm/slub.c:5361 [inline]
__kmalloc_noprof+0x485/0x720 mm/slub.c:5387
_kmalloc_noprof include/linux/slab.h:973 [inline]
load_elf_phdrs fs/binfmt_elf.c:540 [inline]
load_elf_binary+0x2c3/0x2950 fs/binfmt_elf.c:869
search_binary_handler fs/exec.c:1694 [inline]
exec_binprm fs/exec.c:1726 [inline]
bprm_execve+0x9c7/0x1630 fs/exec.c:1778
kernel_execve+0x8c3/0x9c0 fs/exec.c:1922
call_usermodehelper_exec_async+0x20f/0x360 kernel/umh.c:109
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 4986 tgid 4986 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950
__slab_free+0x274/0x2c0 mm/slub.c:5767
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:4612 [inline]
slab_alloc_node mm/slub.c:4945 [inline]
kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4959
alloc_filename fs/namei.c:147 [inline]
do_getname+0x2e/0x250 fs/namei.c:187
class_filename_flags_constructor include/linux/fs.h:2561 [inline]
do_readlinkat+0xc8/0x510 fs/stat.c:569
__do_sys_readlink fs/stat.c:605 [inline]
__se_sys_readlink fs/stat.c:602 [inline]
__x64_sys_readlink+0x7f/0x90 fs/stat.c:602
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff888078b39900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888078b39980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888078b39a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888078b39a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888078b39b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
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.
prev parent reply other threads:[~2026-06-25 19:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-02 10:40 syzbot
2026-06-03 17:16 ` [PATCH] jfs: fix use-after-free in lmLogSync during unmount Jie Wang
2026-06-25 19:01 ` syzbot [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6a3d7b08.80e5668d.5d0ef.0006.GAE@google.com \
--to=syzbot+ea7ed3bb2f444cb4dfeb@syzkaller.appspotmail.com \
--cc=jfs-discussion@lists.sourceforge.net \
--cc=jie.wang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=shaggy@kernel.org \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox