[moderation] [bluetooth?] KASAN: null-ptr-deref Write in l2cap_sock_suspend_cb (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aa54b1d27fe0 rxrpc: Also unshare DATA/RESPONSE packets whe..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14e08950580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f2e8ebfec4636d32
dashboard link: https://syzkaller.appspot.com/bug?extid=01fdd60c7fce19a1f6e7
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [linux-b...@vger.kernel.org linux-...@vger.kernel.org luiz....@gmail.com mar...@holtmann.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8df2efaf7574/disk-aa54b1d2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/92106b8bb139/vmlinux-aa54b1d2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ea5ff7c27190/bzImage-aa54b1d2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+01fdd6...@syzkaller.appspotmail.com

ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
kobject: 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: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:97 [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+0x4a/0x80 net/bluetooth/l2cap_sock.c:1784
Write of size 8 at addr 0000000000000798 by task kworker/u9:1/4916

CPU: 0 UID: 0 PID: 4916 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: hci2 hci_rx_work
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
kasan_report+0x117/0x150 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
instrument_atomic_write include/linux/instrumented.h:97 [inline]
set_bit include/asm-generic/bitops/instrumented-atomic.h:28 [inline]
l2cap_sock_suspend_cb+0x4a/0x80 net/bluetooth/l2cap_sock.c:1784
l2cap_chan_ready+0x15b/0x230 net/bluetooth/l2cap_core.c:1273
l2cap_le_start+0x25b/0x1960 net/bluetooth/l2cap_core.c:1391
l2cap_conn_ready net/bluetooth/l2cap_core.c:1644 [inline]
l2cap_connect_cfm+0x8d5/0x1560 net/bluetooth/l2cap_core.c:7419
hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2139
le_conn_complete_evt+0x1134/0x16b0 net/bluetooth/hci_event.c:5865
hci_le_conn_complete_evt+0x187/0x470 net/bluetooth/hci_event.c:5891
hci_event_func net/bluetooth/hci_event.c:7793 [inline]
hci_event_packet+0x659/0xef0 net/bluetooth/hci_event.c:7847
hci_rx_work+0x3ee/0x1040 net/bluetooth/hci_core.c:4077
process_one_work kernel/workqueue.c:3302 [inline]
process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
==================================================================


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