[v6.6] KASAN: slab-use-after-free Read in jfs_syncpt

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syzbot

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Jun 21, 2025, 5:40:33 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=10058dd4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=1473770ca06b052afcaa
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+147377...@syzkaller.appspotmail.com

==================================================================
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+0x6cb/0xcc0 kernel/locking/mutex.c:747
Read of size 8 at addr ffff888057931108 by task jfsCommit/112

CPU: 1 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
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
__mutex_waiter_is_first kernel/locking/mutex.c:197 [inline]
__mutex_lock_common kernel/locking/mutex.c:681 [inline]
__mutex_lock+0x6cb/0xcc0 kernel/locking/mutex.c:747
jfs_syncpt+0x25/0x90 fs/jfs/jfs_logmgr.c:1039
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 5939:
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 5767:
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 ffff888057931000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 264 bytes inside of
freed 1024-byte region [ffff888057931000, ffff888057931400)

The buggy address belongs to the physical page:
page:ffffea00015e4c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x57930
head:ffffea00015e4c00 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 dead000000000122 0000000000000000
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 0x152820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 42, tgid 42 (kworker/u4:2), ts 83012780176, free_ts 16463852033
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]
kzalloc include/linux/slab.h:721 [inline]
ieee802_11_parse_elems_full+0xb9/0x2080 net/mac80211/util.c:1616
ieee802_11_parse_elems_crc net/mac80211/ieee80211_i.h:2328 [inline]
ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2335 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1609 [inline]
ieee80211_ibss_rx_queued_mgmt+0x49b/0x2ac0 net/mac80211/ibss.c:1642
ieee80211_iface_process_skb net/mac80211/iface.c:1643 [inline]
ieee80211_iface_work+0x717/0xc70 net/mac80211/iface.c:1697
cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
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
free_contig_range+0xa1/0x160 mm/page_alloc.c:6369
destroy_args+0x87/0x770 mm/debug_vm_pgtable.c:1015
debug_vm_pgtable+0x3cc/0x410 mm/debug_vm_pgtable.c:1395
do_one_initcall+0x1fd/0x750 init/main.c:1238
do_initcall_level+0x137/0x1f0 init/main.c:1300
do_initcalls+0x69/0xd0 init/main.c:1316
kernel_init_freeable+0x3d2/0x570 init/main.c:1553
kernel_init+0x1d/0x1c0 init/main.c:1443
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Memory state around the buggy address:
ffff888057931000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888057931080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888057931100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888057931180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888057931200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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syzbot

unread,
Jun 22, 2025, 2:38:31 AM6/22/25
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=1104cdd4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=1473770ca06b052afcaa
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=10f6b30c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1504cdd4580000
mounted in repro: https://storage.googleapis.com/syzbot-assets/1cdfa8e8b2fe/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=12600b0c580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+147377...@syzkaller.appspotmail.com

==================================================================
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+0x6cb/0xcc0 kernel/locking/mutex.c:747
Read of size 8 at addr ffff8880250bd908 by task jfsCommit/112

CPU: 1 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
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
__mutex_waiter_is_first kernel/locking/mutex.c:197 [inline]
__mutex_lock_common kernel/locking/mutex.c:681 [inline]
__mutex_lock+0x6cb/0xcc0 kernel/locking/mutex.c:747
jfs_syncpt+0x25/0x90 fs/jfs/jfs_logmgr.c:1039
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 5811:
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 5774:
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 ffff8880250bd800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 264 bytes inside of
freed 1024-byte region [ffff8880250bd800, ffff8880250bdc00)

The buggy address belongs to the physical page:
page:ffffea0000942e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880250b8000 pfn:0x250b8
head:ffffea0000942e00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017841dc0 0000000000000000 0000000000000001
raw: ffff8880250b8000 000000008010000c 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 5578, tgid 5578 (dhcpcd), ts 42009380068, free_ts 41274233887
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_node+0xa4/0x230 mm/slab_common.c:1014
kmalloc_node include/linux/slab.h:620 [inline]
kvmalloc_node+0x70/0x180 mm/util.c:617
kvmalloc include/linux/slab.h:738 [inline]
kvmalloc_array include/linux/slab.h:756 [inline]
bpf_int_jit_compile+0x34d/0x1130 arch/x86/net/bpf_jit_comp.c:2864
bpf_prog_select_runtime+0x490/0x7e0 kernel/bpf/core.c:2389
bpf_migrate_filter net/core/filter.c:1308 [inline]
bpf_prepare_filter+0x1148/0x12f0 net/core/filter.c:1356
bpf_prog_create_from_user+0x2d2/0x420 net/core/filter.c:1450
seccomp_prepare_filter kernel/seccomp.c:680 [inline]
seccomp_prepare_user_filter kernel/seccomp.c:717 [inline]
seccomp_set_mode_filter kernel/seccomp.c:1935 [inline]
do_seccomp+0x7ac/0xd90 kernel/seccomp.c:2055
__do_sys_prctl kernel/sys.c:2517 [inline]
__se_sys_prctl+0xac4/0x1490 kernel/sys.c:2435
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
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
free_large_kmalloc+0x101/0x1a0 mm/slab_common.c:984
skb_kfree_head net/core/skbuff.c:945 [inline]
skb_free_head net/core/skbuff.c:957 [inline]
skb_release_data+0x634/0x800 net/core/skbuff.c:987
skb_release_all net/core/skbuff.c:1053 [inline]
__kfree_skb net/core/skbuff.c:1067 [inline]
consume_skb+0xb2/0x110 net/core/skbuff.c:1283
netlink_recvmsg+0x5cf/0xdf0 net/netlink/af_netlink.c:1969
sock_recvmsg_nosec net/socket.c:1046 [inline]
sock_recvmsg net/socket.c:1068 [inline]
____sys_recvmsg+0x29e/0x5b0 net/socket.c:2814
___sys_recvmsg+0x1b6/0x510 net/socket.c:2856
__sys_recvmsg net/socket.c:2886 [inline]
__do_sys_recvmsg net/socket.c:2896 [inline]
__se_sys_recvmsg net/socket.c:2893 [inline]
__x64_sys_recvmsg+0x1f2/0x2c0 net/socket.c:2893
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

Memory state around the buggy address:
ffff8880250bd800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880250bd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880250bd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880250bd980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880250bda00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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