[syzbot] [bluetooth?] KASAN: null-ptr-deref Write in l2cap_sock_resume_cb (4)

From: syzbot
Date: Mon Jul 07 2025 - 14:32:42 EST

Next message: David Kaplan: "[PATCH v6 01/21] Documentation/x86: Document new attack vector controls"
Previous message: Michal Kubecek: "Re: [PATCH ethtool-next 2/2] ethtool: pse-pd: Add PSE priority and event monitoring support"
Next in thread: Hillf Danton: "Re: [syzbot] [bluetooth?] KASAN: null-ptr-deref Write in l2cap_sock_resume_cb (4)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hello,

syzbot found the following issue on:

HEAD commit: 7482bb149b9f Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1597828c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3c06e3e2454512b3
dashboard link: https://syzkaller.appspot.com/bug?extid=e2df3a66f7d16fa6ec55
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17c4cbd4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d11f70580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f623d741d651/disk-7482bb14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/483e23ae71b1/vmlinux-7482bb14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/79b5baaa1b50/Image-7482bb14.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e2df3a66f7d16fa6ec55@xxxxxxxxxxxxxxxxxxxxxxxxx

Bluetooth: hci0: unexpected event 0x06 length: 4 > 3
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:82 [inline]
BUG: KASAN: null-ptr-deref in clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
BUG: KASAN: null-ptr-deref in l2cap_sock_resume_cb+0xb4/0x17c net/bluetooth/l2cap_sock.c:1711
Write of size 8 at addr 0000000000000570 by task kworker/u9:0/52

CPU: 1 UID: 0 PID: 52 Comm: kworker/u9:0 Not tainted 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci0 hci_rx_work
Call trace:
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:501 (C)
__dump_stack+0x30/0x40 lib/dump_stack.c:94
dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
print_report+0x58/0x84 mm/kasan/report.c:524
kasan_report+0xb0/0x110 mm/kasan/report.c:634
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:189
__kasan_check_write+0x20/0x30 mm/kasan/shadow.c:37
instrument_atomic_write include/linux/instrumented.h:82 [inline]
clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
l2cap_sock_resume_cb+0xb4/0x17c net/bluetooth/l2cap_sock.c:1711
l2cap_security_cfm+0x524/0xea0 net/bluetooth/l2cap_core.c:7357
hci_auth_cfm include/net/bluetooth/hci_core.h:2092 [inline]
hci_auth_complete_evt+0x2e8/0xa4c net/bluetooth/hci_event.c:3514
hci_event_func net/bluetooth/hci_event.c:7511 [inline]
hci_event_packet+0x650/0xe9c net/bluetooth/hci_event.c:7565
hci_rx_work+0x320/0xb18 net/bluetooth/hci_core.c:4070
process_one_work+0x7e8/0x155c kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x958/0xed8 kernel/workqueue.c:3402
kthread+0x5fc/0x75c kernel/kthread.c:464
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
==================================================================
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000570
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000121d3b000
[0000000000000570] pgd=0800000121d58403, p4d=0800000121d58403, pud=0800000121d81403, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1] SMP
Modules linked in:
CPU: 1 UID: 0 PID: 52 Comm: kworker/u9:0 Tainted: G B 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPT
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci0 hci_rx_work
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __lse_atomic64_andnot arch/arm64/include/asm/atomic_lse.h:131 [inline]
pc : arch_atomic64_andnot arch/arm64/include/asm/atomic.h:64 [inline]
pc : raw_atomic64_andnot include/linux/atomic/atomic-arch-fallback.h:3675 [inline]
pc : raw_atomic_long_andnot include/linux/atomic/atomic-long.h:964 [inline]
pc : arch_clear_bit include/asm-generic/bitops/atomic.h:25 [inline]
pc : clear_bit include/asm-generic/bitops/instrumented-atomic.h:42 [inline]
pc : l2cap_sock_resume_cb+0xc0/0x17c net/bluetooth/l2cap_sock.c:1711
lr : __lse_atomic64_andnot arch/arm64/include/asm/atomic_lse.h:131 [inline]
lr : arch_atomic64_andnot arch/arm64/include/asm/atomic.h:64 [inline]
lr : raw_atomic64_andnot include/linux/atomic/atomic-arch-fallback.h:3675 [inline]
lr : raw_atomic_long_andnot include/linux/atomic/atomic-long.h:964 [inline]
lr : arch_clear_bit include/asm-generic/bitops/atomic.h:25 [inline]
lr : clear_bit include/asm-generic/bitops/instrumented-atomic.h:42 [inline]
lr : l2cap_sock_resume_cb+0xbc/0x17c net/bluetooth/l2cap_sock.c:1711
sp : ffff8000991975b0
x29: ffff8000991975b0 x28: ffff0000d89f6000 x27: dfff800000000000
x26: ffff700013232ec8 x25: 0000000000000001 x24: ffff80008db6f6c0
x23: ffff0000d89f6480 x22: dfff800000000000 x21: 0000000000000002
x20: 0000000000000570 x19: 0000000000000000 x18: 1fffe000337d8876
x17: 0000000000000000 x16: ffff80008ae642c8 x15: 0000000000000001
x14: 1ffff000125d90f8 x13: 0000000000000000 x12: 0000000000000000
x11: ffff7000125d90f9 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 0000000000000002 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800099196e18 x4 : ffff80008f766c20 x3 : ffff8000803b80e0
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
__lse_atomic64_andnot arch/arm64/include/asm/atomic_lse.h:-1 [inline] (P)
arch_atomic64_andnot arch/arm64/include/asm/atomic.h:64 [inline] (P)
raw_atomic64_andnot include/linux/atomic/atomic-arch-fallback.h:3675 [inline] (P)
raw_atomic_long_andnot include/linux/atomic/atomic-long.h:964 [inline] (P)
arch_clear_bit include/asm-generic/bitops/atomic.h:25 [inline] (P)
clear_bit include/asm-generic/bitops/instrumented-atomic.h:42 [inline] (P)
l2cap_sock_resume_cb+0xc0/0x17c net/bluetooth/l2cap_sock.c:1711 (P)
l2cap_security_cfm+0x524/0xea0 net/bluetooth/l2cap_core.c:7357
hci_auth_cfm include/net/bluetooth/hci_core.h:2092 [inline]
hci_auth_complete_evt+0x2e8/0xa4c net/bluetooth/hci_event.c:3514
hci_event_func net/bluetooth/hci_event.c:7511 [inline]
hci_event_packet+0x650/0xe9c net/bluetooth/hci_event.c:7565
hci_rx_work+0x320/0xb18 net/bluetooth/hci_core.c:4070
process_one_work+0x7e8/0x155c kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x958/0xed8 kernel/workqueue.c:3402
kthread+0x5fc/0x75c kernel/kthread.c:464
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
Code: 977fc1f2 d503201f 977fc0f7 52800048 (f828129f)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 977fc1f2 bl 0xfffffffffdff07c8
4: d503201f nop
8: 977fc0f7 bl 0xfffffffffdff03e4
c: 52800048 mov w8, #0x2 // #2
* 10: f828129f stclr x8, [x20] <-- trapping instruction

---
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 syzkaller@xxxxxxxxxxxxxxxx.

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 syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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

Next message: David Kaplan: "[PATCH v6 01/21] Documentation/x86: Document new attack vector controls"
Previous message: Michal Kubecek: "Re: [PATCH ethtool-next 2/2] ethtool: pse-pd: Add PSE priority and event monitoring support"
Next in thread: Hillf Danton: "Re: [syzbot] [bluetooth?] KASAN: null-ptr-deref Write in l2cap_sock_resume_cb (4)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]