[v5.15] KASAN: use-after-free Read in l2cap_sock_ready_cb (4)
0 views
Skip to first unread message
syzbot
Jan 27, 2026, 9:22:26 PM (12 hours ago) Jan 27
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 9eec9a14ee10 Linux 5.15.198
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17bf432a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=890cb7349869e8acc08b
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7146a7b4242e/disk-9eec9a14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a11468b96c22/vmlinux-9eec9a14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e7cb8f058e1c/bzImage-9eec9a14.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+890cb7...@syzkaller.appspotmail.com
</TASK>
kobject_add_internal failed for hci2:201 with -EEXIST, don't try to register things with the same name in the same directory.
Bluetooth: hci2: failed to register connection device
==================================================================
BUG: KASAN: use-after-free in l2cap_sock_ready_cb+0xca/0x120 net/bluetooth/l2cap_sock.c:1662
Read of size 8 at addr ffff88802c30d4c8 by task kworker/u5:3/4196
CPU: 0 PID: 4196 Comm: kworker/u5:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: hci2 hci_rx_work
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
print_address_description+0x60/0x2d0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:434 [inline]
kasan_report+0xdf/0x130 mm/kasan/report.c:451
l2cap_sock_ready_cb+0xca/0x120 net/bluetooth/l2cap_sock.c:1662
l2cap_chan_ready net/bluetooth/l2cap_core.c:1387 [inline]
l2cap_le_start+0x73b/0x1710 net/bluetooth/l2cap_core.c:1499
l2cap_conn_ready net/bluetooth/l2cap_core.c:1769 [inline]
l2cap_connect_cfm+0x6d7/0x10f0 net/bluetooth/l2cap_core.c:8321
hci_connect_cfm include/net/bluetooth/hci_core.h:1505 [inline]
le_conn_complete_evt+0xd42/0x15c0 net/bluetooth/hci_event.c:5456
hci_le_conn_complete_evt net/bluetooth/hci_event.c:5481 [inline]
hci_le_meta_evt+0x285/0x3c90 net/bluetooth/hci_event.c:6203
hci_event_packet+0xe48/0x1370 net/bluetooth/hci_event.c:6552
hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5160
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Allocated by task 5409:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
____kasan_kmalloc mm/kasan/common.c:513 [inline]
__kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
kmalloc include/linux/slab.h:612 [inline]
sk_prot_alloc+0xe7/0x210 net/core/sock.c:1866
sk_alloc+0x2f/0x310 net/core/sock.c:1922
l2cap_sock_alloc+0x33/0x200 net/bluetooth/l2cap_sock.c:1867
l2cap_sock_create+0x118/0x1d0 net/bluetooth/l2cap_sock.c:1915
bt_sock_create+0x155/0x220 net/bluetooth/af_bluetooth.c:130
__sock_create+0x47b/0x900 net/socket.c:1495
sock_create net/socket.c:1551 [inline]
__sys_socket+0xe2/0x170 net/socket.c:1593
__do_sys_socket net/socket.c:1602 [inline]
__se_sys_socket net/socket.c:1600 [inline]
__x64_sys_socket+0x76/0x80 net/socket.c:1600
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
Freed by task 5412:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1710 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kfree+0xef/0x2a0 mm/slub.c:4564
sk_prot_free net/core/sock.c:1905 [inline]
__sk_destruct+0x578/0x840 net/core/sock.c:1991
l2cap_sock_release+0x169/0x1e0 net/bluetooth/l2cap_sock.c:1432
__sock_release net/socket.c:651 [inline]
sock_close+0xd5/0x240 net/socket.c:1345
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
Last potentially related work creation:
kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
__call_rcu kernel/rcu/tree.c:3011 [inline]
call_rcu+0x189/0x950 kernel/rcu/tree.c:3091
netlink_release+0x1369/0x17b0 net/netlink/af_netlink.c:799
__sock_release net/socket.c:651 [inline]
sock_close+0xd5/0x240 net/socket.c:1345
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
The buggy address belongs to the object at ffff88802c30d000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1224 bytes inside of
2048-byte region [ffff88802c30d000, ffff88802c30d800)
The buggy address belongs to the page:
page:ffffea0000b0c200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2c308
head:ffffea0000b0c200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888016c42000
raw: 0000000000000000 0000000000080008 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 1, ts 12555751741, free_ts 0
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
__alloc_pages+0x1ee/0x480 mm/page_alloc.c:5487
alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2031
alloc_slab_page mm/slub.c:1780 [inline]
allocate_slab mm/slub.c:1917 [inline]
new_slab+0xc0/0x4b0 mm/slub.c:1980
___slab_alloc+0x80a/0xdd0 mm/slub.c:3013
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
slab_alloc mm/slub.c:3233 [inline]
kmem_cache_alloc_trace+0x1a5/0x2a0 mm/slub.c:3250
kmalloc include/linux/slab.h:607 [inline]
kzalloc include/linux/slab.h:738 [inline]
ext4_fill_super+0x36b/0x95a0 fs/ext4/super.c:3968
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3034
init_mount+0xda/0x130 fs/init.c:25
do_mount_root+0x97/0x400 init/do_mounts.c:376
mount_block_root+0x1a5/0x540 init/do_mounts.c:415
prepare_namespace+0x1ef/0x230 init/do_mounts.c:645
kernel_init_freeable+0x42a/0x570 init/main.c:1642
page_owner free stack trace missing
Memory state around the buggy address:
ffff88802c30d380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802c30d400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802c30d480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802c30d500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802c30d580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
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: 9eec9a14ee10 Linux 5.15.198
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17bf432a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=890cb7349869e8acc08b
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7146a7b4242e/disk-9eec9a14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a11468b96c22/vmlinux-9eec9a14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e7cb8f058e1c/bzImage-9eec9a14.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+890cb7...@syzkaller.appspotmail.com
</TASK>
kobject_add_internal failed for hci2:201 with -EEXIST, don't try to register things with the same name in the same directory.
Bluetooth: hci2: failed to register connection device
==================================================================
BUG: KASAN: use-after-free in l2cap_sock_ready_cb+0xca/0x120 net/bluetooth/l2cap_sock.c:1662
Read of size 8 at addr ffff88802c30d4c8 by task kworker/u5:3/4196
CPU: 0 PID: 4196 Comm: kworker/u5:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: hci2 hci_rx_work
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
print_address_description+0x60/0x2d0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:434 [inline]
kasan_report+0xdf/0x130 mm/kasan/report.c:451
l2cap_sock_ready_cb+0xca/0x120 net/bluetooth/l2cap_sock.c:1662
l2cap_chan_ready net/bluetooth/l2cap_core.c:1387 [inline]
l2cap_le_start+0x73b/0x1710 net/bluetooth/l2cap_core.c:1499
l2cap_conn_ready net/bluetooth/l2cap_core.c:1769 [inline]
l2cap_connect_cfm+0x6d7/0x10f0 net/bluetooth/l2cap_core.c:8321
hci_connect_cfm include/net/bluetooth/hci_core.h:1505 [inline]
le_conn_complete_evt+0xd42/0x15c0 net/bluetooth/hci_event.c:5456
hci_le_conn_complete_evt net/bluetooth/hci_event.c:5481 [inline]
hci_le_meta_evt+0x285/0x3c90 net/bluetooth/hci_event.c:6203
hci_event_packet+0xe48/0x1370 net/bluetooth/hci_event.c:6552
hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5160
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Allocated by task 5409:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
____kasan_kmalloc mm/kasan/common.c:513 [inline]
__kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
kmalloc include/linux/slab.h:612 [inline]
sk_prot_alloc+0xe7/0x210 net/core/sock.c:1866
sk_alloc+0x2f/0x310 net/core/sock.c:1922
l2cap_sock_alloc+0x33/0x200 net/bluetooth/l2cap_sock.c:1867
l2cap_sock_create+0x118/0x1d0 net/bluetooth/l2cap_sock.c:1915
bt_sock_create+0x155/0x220 net/bluetooth/af_bluetooth.c:130
__sock_create+0x47b/0x900 net/socket.c:1495
sock_create net/socket.c:1551 [inline]
__sys_socket+0xe2/0x170 net/socket.c:1593
__do_sys_socket net/socket.c:1602 [inline]
__se_sys_socket net/socket.c:1600 [inline]
__x64_sys_socket+0x76/0x80 net/socket.c:1600
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
Freed by task 5412:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1710 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kfree+0xef/0x2a0 mm/slub.c:4564
sk_prot_free net/core/sock.c:1905 [inline]
__sk_destruct+0x578/0x840 net/core/sock.c:1991
l2cap_sock_release+0x169/0x1e0 net/bluetooth/l2cap_sock.c:1432
__sock_release net/socket.c:651 [inline]
sock_close+0xd5/0x240 net/socket.c:1345
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
Last potentially related work creation:
kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
__call_rcu kernel/rcu/tree.c:3011 [inline]
call_rcu+0x189/0x950 kernel/rcu/tree.c:3091
netlink_release+0x1369/0x17b0 net/netlink/af_netlink.c:799
__sock_release net/socket.c:651 [inline]
sock_close+0xd5/0x240 net/socket.c:1345
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
The buggy address belongs to the object at ffff88802c30d000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1224 bytes inside of
2048-byte region [ffff88802c30d000, ffff88802c30d800)
The buggy address belongs to the page:
page:ffffea0000b0c200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2c308
head:ffffea0000b0c200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888016c42000
raw: 0000000000000000 0000000000080008 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 1, ts 12555751741, free_ts 0
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
__alloc_pages+0x1ee/0x480 mm/page_alloc.c:5487
alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2031
alloc_slab_page mm/slub.c:1780 [inline]
allocate_slab mm/slub.c:1917 [inline]
new_slab+0xc0/0x4b0 mm/slub.c:1980
___slab_alloc+0x80a/0xdd0 mm/slub.c:3013
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
slab_alloc mm/slub.c:3233 [inline]
kmem_cache_alloc_trace+0x1a5/0x2a0 mm/slub.c:3250
kmalloc include/linux/slab.h:607 [inline]
kzalloc include/linux/slab.h:738 [inline]
ext4_fill_super+0x36b/0x95a0 fs/ext4/super.c:3968
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3034
init_mount+0xda/0x130 fs/init.c:25
do_mount_root+0x97/0x400 init/do_mounts.c:376
mount_block_root+0x1a5/0x540 init/do_mounts.c:415
prepare_namespace+0x1ef/0x230 init/do_mounts.c:645
kernel_init_freeable+0x42a/0x570 init/main.c:1642
page_owner free stack trace missing
Memory state around the buggy address:
ffff88802c30d380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802c30d400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802c30d480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802c30d500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802c30d580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
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
Reply all
Reply to author
Forward
0 new messages