[v5.15] KASAN: use-after-free Read in l2cap_sock_new_connection_cb
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syzbot
May 22, 2025, 7:53:41 AM5/22/25
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: a68c15152131 Linux 5.15.183
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17bd8170580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ef02e502f5873d8
dashboard link: https://syzkaller.appspot.com/bug?extid=286359dae55ee708bf86
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/9057058298cc/disk-a68c1515.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3e83bf000c3a/vmlinux-a68c1515.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6809226eafd9/bzImage-a68c1515.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+286359...@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_new_connection_cb+0x125/0x1c0 net/bluetooth/l2cap_sock.c:1491
Read of size 8 at addr ffff888061529548 by task kworker/u5:3/4176
CPU: 0 PID: 4176 Comm: kworker/u5:3 Not tainted 5.15.183-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci2 hci_rx_work
Call Trace:
<TASK>
dump_stack_lvl+0x168/0x230 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_new_connection_cb+0x125/0x1c0 net/bluetooth/l2cap_sock.c:1491
l2cap_connect_cfm+0x35d/0x10d0 net/bluetooth/l2cap_core.c:8278
hci_connect_cfm include/net/bluetooth/hci_core.h:1505 [inline]
le_conn_complete_evt+0xdaf/0x1590 net/bluetooth/hci_event.c:5429
hci_le_conn_complete_evt net/bluetooth/hci_event.c:5454 [inline]
hci_le_meta_evt+0x289/0x3b80 net/bluetooth/hci_event.c:6176
hci_event_packet+0xe05/0x12f0 net/bluetooth/hci_event.c:6525
hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5160
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 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 4176:
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:609 [inline]
sk_prot_alloc+0xe7/0x210 net/core/sock.c:1864
sk_alloc+0x2f/0x310 net/core/sock.c:1917
l2cap_sock_alloc+0x33/0x200 net/bluetooth/l2cap_sock.c:1861
l2cap_sock_new_connection_cb+0xd1/0x1c0 net/bluetooth/l2cap_sock.c:1476
l2cap_connect_cfm+0x35d/0x10d0 net/bluetooth/l2cap_core.c:8278
hci_connect_cfm include/net/bluetooth/hci_core.h:1505 [inline]
le_conn_complete_evt+0xdaf/0x1590 net/bluetooth/hci_event.c:5429
hci_le_conn_complete_evt net/bluetooth/hci_event.c:5454 [inline]
hci_le_meta_evt+0x289/0x3b80 net/bluetooth/hci_event.c:6176
hci_event_packet+0xe05/0x12f0 net/bluetooth/hci_event.c:6525
hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5160
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Freed by task 5153:
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:1705 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1731
slab_free mm/slub.c:3499 [inline]
kfree+0xef/0x2a0 mm/slub.c:4559
sk_prot_free net/core/sock.c:1900 [inline]
__sk_destruct+0x55a/0x820 net/core/sock.c:1986
l2cap_sock_cleanup_listen+0xda/0x270 net/bluetooth/l2cap_sock.c:1456
l2cap_sock_release+0x59/0x1c0 net/bluetooth/l2cap_sock.c:1419
__sock_release net/socket.c:649 [inline]
sock_close+0xd5/0x240 net/socket.c:1336
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
get_signal+0x1222/0x12c0 kernel/signal.c:2672
arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:154 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
exit_to_user_mode_prepare+0xb1/0x140 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 ffff888061529000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1352 bytes inside of
2048-byte region [ffff888061529000, ffff888061529800)
The buggy address belongs to the page:
page:ffffea0001854a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x61528
head:ffffea0001854a00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 0000000100000001 ffff888016842000
raw: 0000000000000000 0000000080080008 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 0xd2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4168, ts 71698156350, free_ts 25358115762
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
__alloc_pages+0x1e1/0x470 mm/page_alloc.c:5466
alloc_slab_page mm/slub.c:1775 [inline]
allocate_slab mm/slub.c:1912 [inline]
new_slab+0xc0/0x4b0 mm/slub.c:1975
___slab_alloc+0x81e/0xdf0 mm/slub.c:3008
__slab_alloc mm/slub.c:3095 [inline]
slab_alloc_node mm/slub.c:3186 [inline]
__kmalloc_node_track_caller+0x1fc/0x3a0 mm/slub.c:4958
kmalloc_reserve net/core/skbuff.c:356 [inline]
pskb_expand_head+0x127/0x10f0 net/core/skbuff.c:1709
netlink_trim+0x180/0x220 net/netlink/af_netlink.c:1293
netlink_broadcast_filtered+0x7c/0x1170 net/netlink/af_netlink.c:1498
netlink_broadcast net/netlink/af_netlink.c:1543 [inline]
nlmsg_multicast include/net/netlink.h:1033 [inline]
nlmsg_notify+0xec/0x1a0 net/netlink/af_netlink.c:2532
__dev_notify_flags+0xde/0x2d0 net/core/dev.c:8887
dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
do_setlink+0xc01/0x3980 net/core/rtnetlink.c:2779
__rtnl_newlink net/core/rtnetlink.c:3450 [inline]
rtnl_newlink+0x1419/0x17d0 net/core/rtnetlink.c:3572
rtnetlink_rcv_msg+0x9b9/0xe60 net/core/rtnetlink.c:5650
netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2489
netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
netlink_unicast+0x77c/0x920 net/netlink/af_netlink.c:1337
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1340 [inline]
free_pcp_prepare mm/page_alloc.c:1391 [inline]
free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
free_unref_page+0x94/0x280 mm/page_alloc.c:3396
free_contig_range+0x96/0xf0 mm/page_alloc.c:9385
destroy_args+0xef/0x8b0 mm/debug_vm_pgtable.c:1018
debug_vm_pgtable+0x318/0x370 mm/debug_vm_pgtable.c:1331
do_one_initcall+0x1ee/0x680 init/main.c:1302
do_initcall_level+0x137/0x1f0 init/main.c:1375
do_initcalls+0x4b/0x90 init/main.c:1391
kernel_init_freeable+0x3ce/0x560 init/main.c:1615
kernel_init+0x19/0x1b0 init/main.c:1506
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Memory state around the buggy address:
ffff888061529400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888061529480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888061529500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888061529580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888061529600: 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: a68c15152131 Linux 5.15.183
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17bd8170580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ef02e502f5873d8
dashboard link: https://syzkaller.appspot.com/bug?extid=286359dae55ee708bf86
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/9057058298cc/disk-a68c1515.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3e83bf000c3a/vmlinux-a68c1515.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6809226eafd9/bzImage-a68c1515.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+286359...@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_new_connection_cb+0x125/0x1c0 net/bluetooth/l2cap_sock.c:1491
Read of size 8 at addr ffff888061529548 by task kworker/u5:3/4176
CPU: 0 PID: 4176 Comm: kworker/u5:3 Not tainted 5.15.183-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci2 hci_rx_work
Call Trace:
<TASK>
dump_stack_lvl+0x168/0x230 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_new_connection_cb+0x125/0x1c0 net/bluetooth/l2cap_sock.c:1491
l2cap_connect_cfm+0x35d/0x10d0 net/bluetooth/l2cap_core.c:8278
hci_connect_cfm include/net/bluetooth/hci_core.h:1505 [inline]
le_conn_complete_evt+0xdaf/0x1590 net/bluetooth/hci_event.c:5429
hci_le_conn_complete_evt net/bluetooth/hci_event.c:5454 [inline]
hci_le_meta_evt+0x289/0x3b80 net/bluetooth/hci_event.c:6176
hci_event_packet+0xe05/0x12f0 net/bluetooth/hci_event.c:6525
hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5160
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 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 4176:
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:609 [inline]
sk_prot_alloc+0xe7/0x210 net/core/sock.c:1864
sk_alloc+0x2f/0x310 net/core/sock.c:1917
l2cap_sock_alloc+0x33/0x200 net/bluetooth/l2cap_sock.c:1861
l2cap_sock_new_connection_cb+0xd1/0x1c0 net/bluetooth/l2cap_sock.c:1476
l2cap_connect_cfm+0x35d/0x10d0 net/bluetooth/l2cap_core.c:8278
hci_connect_cfm include/net/bluetooth/hci_core.h:1505 [inline]
le_conn_complete_evt+0xdaf/0x1590 net/bluetooth/hci_event.c:5429
hci_le_conn_complete_evt net/bluetooth/hci_event.c:5454 [inline]
hci_le_meta_evt+0x289/0x3b80 net/bluetooth/hci_event.c:6176
hci_event_packet+0xe05/0x12f0 net/bluetooth/hci_event.c:6525
hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5160
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Freed by task 5153:
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:1705 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1731
slab_free mm/slub.c:3499 [inline]
kfree+0xef/0x2a0 mm/slub.c:4559
sk_prot_free net/core/sock.c:1900 [inline]
__sk_destruct+0x55a/0x820 net/core/sock.c:1986
l2cap_sock_cleanup_listen+0xda/0x270 net/bluetooth/l2cap_sock.c:1456
l2cap_sock_release+0x59/0x1c0 net/bluetooth/l2cap_sock.c:1419
__sock_release net/socket.c:649 [inline]
sock_close+0xd5/0x240 net/socket.c:1336
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
get_signal+0x1222/0x12c0 kernel/signal.c:2672
arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:154 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
exit_to_user_mode_prepare+0xb1/0x140 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 ffff888061529000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1352 bytes inside of
2048-byte region [ffff888061529000, ffff888061529800)
The buggy address belongs to the page:
page:ffffea0001854a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x61528
head:ffffea0001854a00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 0000000100000001 ffff888016842000
raw: 0000000000000000 0000000080080008 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 0xd2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4168, ts 71698156350, free_ts 25358115762
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
__alloc_pages+0x1e1/0x470 mm/page_alloc.c:5466
alloc_slab_page mm/slub.c:1775 [inline]
allocate_slab mm/slub.c:1912 [inline]
new_slab+0xc0/0x4b0 mm/slub.c:1975
___slab_alloc+0x81e/0xdf0 mm/slub.c:3008
__slab_alloc mm/slub.c:3095 [inline]
slab_alloc_node mm/slub.c:3186 [inline]
__kmalloc_node_track_caller+0x1fc/0x3a0 mm/slub.c:4958
kmalloc_reserve net/core/skbuff.c:356 [inline]
pskb_expand_head+0x127/0x10f0 net/core/skbuff.c:1709
netlink_trim+0x180/0x220 net/netlink/af_netlink.c:1293
netlink_broadcast_filtered+0x7c/0x1170 net/netlink/af_netlink.c:1498
netlink_broadcast net/netlink/af_netlink.c:1543 [inline]
nlmsg_multicast include/net/netlink.h:1033 [inline]
nlmsg_notify+0xec/0x1a0 net/netlink/af_netlink.c:2532
__dev_notify_flags+0xde/0x2d0 net/core/dev.c:8887
dev_change_flags+0xe3/0x1a0 net/core/dev.c:8929
do_setlink+0xc01/0x3980 net/core/rtnetlink.c:2779
__rtnl_newlink net/core/rtnetlink.c:3450 [inline]
rtnl_newlink+0x1419/0x17d0 net/core/rtnetlink.c:3572
rtnetlink_rcv_msg+0x9b9/0xe60 net/core/rtnetlink.c:5650
netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2489
netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
netlink_unicast+0x77c/0x920 net/netlink/af_netlink.c:1337
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1340 [inline]
free_pcp_prepare mm/page_alloc.c:1391 [inline]
free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
free_unref_page+0x94/0x280 mm/page_alloc.c:3396
free_contig_range+0x96/0xf0 mm/page_alloc.c:9385
destroy_args+0xef/0x8b0 mm/debug_vm_pgtable.c:1018
debug_vm_pgtable+0x318/0x370 mm/debug_vm_pgtable.c:1331
do_one_initcall+0x1ee/0x680 init/main.c:1302
do_initcall_level+0x137/0x1f0 init/main.c:1375
do_initcalls+0x4b/0x90 init/main.c:1391
kernel_init_freeable+0x3ce/0x560 init/main.c:1615
kernel_init+0x19/0x1b0 init/main.c:1506
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Memory state around the buggy address:
ffff888061529400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888061529480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888061529500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888061529580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888061529600: 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
Nov 24, 2025, 12:00:19 PM11/24/25
to syzkaller...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
Crashes did not happen for a while, no reproducer and no activity.
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