[v6.6] KASAN: null-ptr-deref Write in l2cap_sock_suspend_cb

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f5b4c104b7d Linux 6.6.95
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17f8ac8c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=747dbf84b0ecd30c
dashboard link: https://syzkaller.appspot.com/bug?extid=f71734cbee2497be9eae
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/421f6e2d0cd1/disk-3f5b4c10.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/90250695b20b/vmlinux-3f5b4c10.xz
kernel image: https://storage.googleapis.com/syzbot-assets/32250e77bce9/bzImage-3f5b4c10.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f71734...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:82 [inline]
BUG: KASAN: null-ptr-deref in set_bit include/asm-generic/bitops/instrumented-atomic.h:28 [inline]
BUG: KASAN: null-ptr-deref in l2cap_sock_suspend_cb+0x4c/0x80 net/bluetooth/l2cap_sock.c:1726
Write of size 8 at addr 0000000000000528 by task kworker/u5:3/15776

CPU: 1 PID: 15776 Comm: kworker/u5:3 Not tainted 6.6.95-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+0x16c/0x230 lib/dump_stack.c:106
kasan_report+0x117/0x150 mm/kasan/report.c:588
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
instrument_atomic_write include/linux/instrumented.h:82 [inline]
set_bit include/asm-generic/bitops/instrumented-atomic.h:28 [inline]
l2cap_sock_suspend_cb+0x4c/0x80 net/bluetooth/l2cap_sock.c:1726
l2cap_chan_ready net/bluetooth/l2cap_core.c:1257 [inline]
l2cap_le_start+0xa9d/0x1370 net/bluetooth/l2cap_core.c:1375
l2cap_conn_ready net/bluetooth/l2cap_core.c:1628 [inline]
l2cap_connect_cfm+0x6b9/0x1030 net/bluetooth/l2cap_core.c:7252
hci_connect_cfm+0x8f/0x130 include/net/bluetooth/hci_core.h:1968
le_conn_complete_evt+0xcd0/0x1220 net/bluetooth/hci_event.c:5772
hci_le_conn_complete_evt+0x187/0x440 net/bluetooth/hci_event.c:5798
hci_event_func net/bluetooth/hci_event.c:7433 [inline]
hci_event_packet+0x795/0x1210 net/bluetooth/hci_event.c:7488
hci_rx_work+0x43a/0xd80 net/bluetooth/hci_core.c:3992
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
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.