[v6.6] general protection fault in lmLogSync
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syzbot
Jun 21, 2025, 5:37:29 AM6/21/25
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11303370580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=fd016b483ce9e23a110b
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fd016b...@syzkaller.appspotmail.com
general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
CPU: 0 PID: 112 Comm: jfsCommit Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:write_special_inodes fs/jfs/jfs_logmgr.c:208 [inline]
RIP: 0010:lmLogSync+0x139/0x9c0 fs/jfs/jfs_logmgr.c:935
Code: a9 b3 fe 4d 8d 7e f0 4c 89 f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 55 84 dd fe 4d 8b 3f 49 83 c7 40 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ff e8 39 84 dd fe 49 8b 3f e8 01 a9 b3 fe
RSP: 0018:ffffc900015c7c40 EFLAGS: 00010202
RAX: 0000000000000008 RBX: dffffc0000000000 RCX: 6fa56670fbfad500
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900015c7d48 R08: 0000000000000004 R09: 0000000000000004
R10: ffffc900015c7b64 R11: fffff520002b8f75 R12: ffff88807c1cc000
R13: dffffc0000000000 R14: ffff88801c335c38 R15: 0000000000000040
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fccfaf7f000 CR3: 0000000019a9b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
jfs_syncpt+0x7b/0x90 fs/jfs/jfs_logmgr.c:1041
txEnd+0x2e5/0x520 fs/jfs/jfs_txnmgr.c:549
txLazyCommit fs/jfs/jfs_txnmgr.c:2684 [inline]
jfs_lazycommit+0x5a6/0xa60 fs/jfs/jfs_txnmgr.c:2732
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>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:write_special_inodes fs/jfs/jfs_logmgr.c:208 [inline]
RIP: 0010:lmLogSync+0x139/0x9c0 fs/jfs/jfs_logmgr.c:935
Code: a9 b3 fe 4d 8d 7e f0 4c 89 f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 55 84 dd fe 4d 8b 3f 49 83 c7 40 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ff e8 39 84 dd fe 49 8b 3f e8 01 a9 b3 fe
RSP: 0018:ffffc900015c7c40 EFLAGS: 00010202
RAX: 0000000000000008 RBX: dffffc0000000000 RCX: 6fa56670fbfad500
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900015c7d48 R08: 0000000000000004 R09: 0000000000000004
R10: ffffc900015c7b64 R11: fffff520002b8f75 R12: ffff88807c1cc000
R13: dffffc0000000000 R14: ffff88801c335c38 R15: 0000000000000040
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fde4c5a0e9c CR3: 000000000cb30000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: a9 b3 fe 4d 8d test $0x8d4dfeb3,%eax
5: 7e f0 jle 0xfffffff7
7: 4c 89 f8 mov %r15,%rax
a: 48 c1 e8 03 shr $0x3,%rax
e: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1)
12: 74 08 je 0x1c
14: 4c 89 ff mov %r15,%rdi
17: e8 55 84 dd fe call 0xfedd8471
1c: 4d 8b 3f mov (%r15),%r15
1f: 49 83 c7 40 add $0x40,%r15
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 ff mov %r15,%rdi
33: e8 39 84 dd fe call 0xfedd8471
38: 49 8b 3f mov (%r15),%rdi
3b: e8 01 a9 b3 fe call 0xfeb3a941
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11303370580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=fd016b483ce9e23a110b
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fd016b...@syzkaller.appspotmail.com
general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
CPU: 0 PID: 112 Comm: jfsCommit Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:write_special_inodes fs/jfs/jfs_logmgr.c:208 [inline]
RIP: 0010:lmLogSync+0x139/0x9c0 fs/jfs/jfs_logmgr.c:935
Code: a9 b3 fe 4d 8d 7e f0 4c 89 f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 55 84 dd fe 4d 8b 3f 49 83 c7 40 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ff e8 39 84 dd fe 49 8b 3f e8 01 a9 b3 fe
RSP: 0018:ffffc900015c7c40 EFLAGS: 00010202
RAX: 0000000000000008 RBX: dffffc0000000000 RCX: 6fa56670fbfad500
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900015c7d48 R08: 0000000000000004 R09: 0000000000000004
R10: ffffc900015c7b64 R11: fffff520002b8f75 R12: ffff88807c1cc000
R13: dffffc0000000000 R14: ffff88801c335c38 R15: 0000000000000040
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fccfaf7f000 CR3: 0000000019a9b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
jfs_syncpt+0x7b/0x90 fs/jfs/jfs_logmgr.c:1041
txEnd+0x2e5/0x520 fs/jfs/jfs_txnmgr.c:549
txLazyCommit fs/jfs/jfs_txnmgr.c:2684 [inline]
jfs_lazycommit+0x5a6/0xa60 fs/jfs/jfs_txnmgr.c:2732
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>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:write_special_inodes fs/jfs/jfs_logmgr.c:208 [inline]
RIP: 0010:lmLogSync+0x139/0x9c0 fs/jfs/jfs_logmgr.c:935
Code: a9 b3 fe 4d 8d 7e f0 4c 89 f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 55 84 dd fe 4d 8b 3f 49 83 c7 40 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ff e8 39 84 dd fe 49 8b 3f e8 01 a9 b3 fe
RSP: 0018:ffffc900015c7c40 EFLAGS: 00010202
RAX: 0000000000000008 RBX: dffffc0000000000 RCX: 6fa56670fbfad500
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900015c7d48 R08: 0000000000000004 R09: 0000000000000004
R10: ffffc900015c7b64 R11: fffff520002b8f75 R12: ffff88807c1cc000
R13: dffffc0000000000 R14: ffff88801c335c38 R15: 0000000000000040
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fde4c5a0e9c CR3: 000000000cb30000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: a9 b3 fe 4d 8d test $0x8d4dfeb3,%eax
5: 7e f0 jle 0xfffffff7
7: 4c 89 f8 mov %r15,%rax
a: 48 c1 e8 03 shr $0x3,%rax
e: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1)
12: 74 08 je 0x1c
14: 4c 89 ff mov %r15,%rdi
17: e8 55 84 dd fe call 0xfedd8471
1c: 4d 8b 3f mov (%r15),%r15
1f: 49 83 c7 40 add $0x40,%r15
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 ff mov %r15,%rdi
33: e8 39 84 dd fe call 0xfedd8471
38: 49 8b 3f mov (%r15),%rdi
3b: e8 01 a9 b3 fe call 0xfeb3a941
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot
Jun 21, 2025, 10:58:20 PM6/21/25
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16eb4dd4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14142182580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f009a726e5eb/mount_1.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=16d2b370580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fd016b...@syzkaller.appspotmail.com
... Log Wrap ... Log Wrap ... Log Wrap ...
==================================================================
BUG: KASAN: slab-use-after-free in lmLogSync+0x92d/0x9c0 fs/jfs/jfs_logmgr.c:1005
Write of size 4 at addr ffff88802300c220 by task jfsCommit/111
CPU: 1 PID: 111 Comm: jfsCommit Not tainted 6.6.94-syzkaller #0
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x230 mm/kasan/report.c:475
kasan_report+0x117/0x150 mm/kasan/report.c:588
lmLogSync+0x92d/0x9c0 fs/jfs/jfs_logmgr.c:1005
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
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+0xea/0x670 fs/jfs/jfs_mount.c:257
jfs_fill_super+0x592/0xac0 fs/jfs/super.c:565
mount_bdev+0x22b/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:3366
do_mount fs/namespace.c:3706 [inline]
__do_sys_mount fs/namespace.c:3915 [inline]
__se_sys_mount+0x2da/0x3c0 fs/namespace.c:3892
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 5775:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1806 [inline]
slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1832
slab_free mm/slub.c:3816 [inline]
__kmem_cache_free+0xba/0x1f0 mm/slub.c:3829
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+0x429/0x4c0 fs/namespace.c:1250
task_work_run+0x1ce/0x250 kernel/task_work.c:239
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+0xb1/0x140 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+0x61/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff88802300c000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 544 bytes inside of
freed 1024-byte region [ffff88802300c000, ffff88802300c400)
The buggy address belongs to the physical page:
page:ffffea00008c0200 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802300b000 pfn:0x23008
head:ffffea00008c0200 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 ffff888017841dc0 ffffea000531de00 0000000000000002
raw: ffff88802300b000 000000008010000f 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5537, tgid 5537 (dhcpcd), ts 41945987300, free_ts 41913143066
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
alloc_slab_page+0x5d/0x170 mm/slub.c:1876
allocate_slab mm/slub.c:2023 [inline]
new_slab+0x87/0x2e0 mm/slub.c:2076
___slab_alloc+0xc6d/0x12f0 mm/slub.c:3230
__slab_alloc mm/slub.c:3329 [inline]
__slab_alloc_node mm/slub.c:3382 [inline]
slab_alloc_node mm/slub.c:3475 [inline]
__kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3524
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa4/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
load_elf_phdrs+0x136/0x230 fs/binfmt_elf.c:512
load_elf_binary+0x956/0x2700 fs/binfmt_elf.c:986
search_binary_handler fs/exec.c:1775 [inline]
exec_binprm fs/exec.c:1817 [inline]
bprm_execve+0xaeb/0x16f0 fs/exec.c:1892
do_execveat_common+0x51b/0x6c0 fs/exec.c:1998
do_execve fs/exec.c:2072 [inline]
__do_sys_execve fs/exec.c:2148 [inline]
__se_sys_execve fs/exec.c:2143 [inline]
__x64_sys_execve+0x92/0xa0 fs/exec.c:2143
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2122 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2662
put_cpu_partial+0x17c/0x250 mm/slub.c:2738
__slab_free+0x31d/0x410 mm/slub.c:3686
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3485 [inline]
kmem_cache_alloc_node+0x150/0x330 mm/slub.c:3530
__alloc_skb+0x108/0x2c0 net/core/skbuff.c:640
alloc_skb include/linux/skbuff.h:1284 [inline]
alloc_skb_with_frags+0xca/0x7c0 net/core/skbuff.c:6328
sock_alloc_send_pskb+0x857/0x990 net/core/sock.c:2799
unix_dgram_sendmsg+0x5a1/0x1720 net/unix/af_unix.c:1949
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_write_iter+0x2bb/0x3f0 net/socket.c:1160
do_iter_readv_writev fs/read_write.c:-1 [inline]
do_iter_write+0x79a/0xc70 fs/read_write.c:860
Memory state around the buggy address:
ffff88802300c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802300c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802300c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802300c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802300c300: 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.
HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=fd016b483ce9e23a110b
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11d2b370580000
dashboard link: https://syzkaller.appspot.com/bug?extid=fd016b483ce9e23a110b
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14142182580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=16d2b370580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fd016b...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in lmLogSync+0x92d/0x9c0 fs/jfs/jfs_logmgr.c:1005
Write of size 4 at addr ffff88802300c220 by task jfsCommit/111
CPU: 1 PID: 111 Comm: jfsCommit Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x230 mm/kasan/report.c:475
kasan_report+0x117/0x150 mm/kasan/report.c:588
lmLogSync+0x92d/0x9c0 fs/jfs/jfs_logmgr.c:1005
jfs_syncpt+0x7b/0x90 fs/jfs/jfs_logmgr.c:1041
txEnd+0x2e5/0x520 fs/jfs/jfs_txnmgr.c:549
txLazyCommit fs/jfs/jfs_txnmgr.c:2684 [inline]
jfs_lazycommit+0x5a6/0xa60 fs/jfs/jfs_txnmgr.c:2732
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 6037:
txEnd+0x2e5/0x520 fs/jfs/jfs_txnmgr.c:549
txLazyCommit fs/jfs/jfs_txnmgr.c:2684 [inline]
jfs_lazycommit+0x5a6/0xa60 fs/jfs/jfs_txnmgr.c:2732
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>
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
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+0xea/0x670 fs/jfs/jfs_mount.c:257
jfs_fill_super+0x592/0xac0 fs/jfs/super.c:565
mount_bdev+0x22b/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:3366
do_mount fs/namespace.c:3706 [inline]
__do_sys_mount fs/namespace.c:3915 [inline]
__se_sys_mount+0x2da/0x3c0 fs/namespace.c:3892
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 5775:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1806 [inline]
slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1832
slab_free mm/slub.c:3816 [inline]
__kmem_cache_free+0xba/0x1f0 mm/slub.c:3829
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+0x429/0x4c0 fs/namespace.c:1250
task_work_run+0x1ce/0x250 kernel/task_work.c:239
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+0xb1/0x140 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+0x61/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff88802300c000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 544 bytes inside of
freed 1024-byte region [ffff88802300c000, ffff88802300c400)
The buggy address belongs to the physical page:
page:ffffea00008c0200 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802300b000 pfn:0x23008
head:ffffea00008c0200 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 ffff888017841dc0 ffffea000531de00 0000000000000002
raw: ffff88802300b000 000000008010000f 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5537, tgid 5537 (dhcpcd), ts 41945987300, free_ts 41913143066
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
alloc_slab_page+0x5d/0x170 mm/slub.c:1876
allocate_slab mm/slub.c:2023 [inline]
new_slab+0x87/0x2e0 mm/slub.c:2076
___slab_alloc+0xc6d/0x12f0 mm/slub.c:3230
__slab_alloc mm/slub.c:3329 [inline]
__slab_alloc_node mm/slub.c:3382 [inline]
slab_alloc_node mm/slub.c:3475 [inline]
__kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3524
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa4/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
load_elf_phdrs+0x136/0x230 fs/binfmt_elf.c:512
load_elf_binary+0x956/0x2700 fs/binfmt_elf.c:986
search_binary_handler fs/exec.c:1775 [inline]
exec_binprm fs/exec.c:1817 [inline]
bprm_execve+0xaeb/0x16f0 fs/exec.c:1892
do_execveat_common+0x51b/0x6c0 fs/exec.c:1998
do_execve fs/exec.c:2072 [inline]
__do_sys_execve fs/exec.c:2148 [inline]
__se_sys_execve fs/exec.c:2143 [inline]
__x64_sys_execve+0x92/0xa0 fs/exec.c:2143
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2122 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2662
put_cpu_partial+0x17c/0x250 mm/slub.c:2738
__slab_free+0x31d/0x410 mm/slub.c:3686
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3485 [inline]
kmem_cache_alloc_node+0x150/0x330 mm/slub.c:3530
__alloc_skb+0x108/0x2c0 net/core/skbuff.c:640
alloc_skb include/linux/skbuff.h:1284 [inline]
alloc_skb_with_frags+0xca/0x7c0 net/core/skbuff.c:6328
sock_alloc_send_pskb+0x857/0x990 net/core/sock.c:2799
unix_dgram_sendmsg+0x5a1/0x1720 net/unix/af_unix.c:1949
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_write_iter+0x2bb/0x3f0 net/socket.c:1160
do_iter_readv_writev fs/read_write.c:-1 [inline]
do_iter_write+0x79a/0xc70 fs/read_write.c:860
Memory state around the buggy address:
ffff88802300c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802300c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802300c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802300c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802300c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
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#syz test: git://repo/address.git branch-or-commit-hash
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