[moderation] [bluetooth?] general protection fault in l2cap_publish_rx_avail

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c3f38fa61af7 Linux 6.10-rc2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12ce97d6980000
kernel config: https://syzkaller.appspot.com/x/.config?x=998c63c06e77f5e7
dashboard link: https://syzkaller.appspot.com/bug?extid=7be7973bcb9d5930918f
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
CC: [johan....@gmail.com 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 (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-c3f38fa6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/af6a0b581dee/vmlinux-c3f38fa6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47864da8bd74/bzImage-c3f38fa6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7be797...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc000000002e: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000170-0x0000000000000177]
CPU: 3 PID: 5244 Comm: kworker/u33:7 Not tainted 6.10.0-rc2-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: hci3 hci_rx_work
RIP: 0010:l2cap_publish_rx_avail+0x4f/0x1c0 net/bluetooth/l2cap_sock.c:1137
Code: 03 80 3c 02 00 0f 85 86 01 00 00 48 8b ab a0 04 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d bd 74 01 00 00 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 3a
RSP: 0018:ffffc90002b8f980 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88802050d000 RCX: ffffc900286bd000
RDX: 000000000000002e RSI: ffffffff89df374e RDI: 0000000000000174
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000003 R12: ffff88802050f000
R13: ffff888025c34a00 R14: ffff88802050d02e R15: ffff888025c34a00
FS: 0000000000000000(0000) GS:ffff88802c300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f5e38fe8 CR3: 0000000056a34000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
l2cap_sock_recv_cb+0x104/0x3d0 net/bluetooth/l2cap_sock.c:1509
l2cap_conless_channel net/bluetooth/l2cap_core.c:6780 [inline]
l2cap_recv_frame+0x20d0/0xa080 net/bluetooth/l2cap_core.c:6833
l2cap_recv_acldata+0x9ac/0xb60 net/bluetooth/l2cap_core.c:7516
hci_acldata_packet net/bluetooth/hci_core.c:3842 [inline]
hci_rx_work+0xaa7/0x1610 net/bluetooth/hci_core.c:4079
process_one_work+0x958/0x1ad0 kernel/workqueue.c:3231
process_scheduled_works kernel/workqueue.c:3312 [inline]
worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:l2cap_publish_rx_avail+0x4f/0x1c0 net/bluetooth/l2cap_sock.c:1137
Code: 03 80 3c 02 00 0f 85 86 01 00 00 48 8b ab a0 04 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d bd 74 01 00 00 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 3a
RSP: 0018:ffffc90002b8f980 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88802050d000 RCX: ffffc900286bd000
RDX: 000000000000002e RSI: ffffffff89df374e RDI: 0000000000000174
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000003 R12: ffff88802050f000
R13: ffff888025c34a00 R14: ffff88802050d02e R15: ffff888025c34a00
FS: 0000000000000000(0000) GS:ffff88802c300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f5e38fe8 CR3: 000000000d97a000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 03 80 3c 02 00 0f add 0xf00023c(%rax),%eax
6: 85 86 01 00 00 48 test %eax,0x48000001(%rsi)
c: 8b ab a0 04 00 00 mov 0x4a0(%rbx),%ebp
12: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
19: fc ff df
1c: 48 8d bd 74 01 00 00 lea 0x174(%rbp),%rdi
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction
2e: 48 89 f8 mov %rdi,%rax
31: 83 e0 07 and $0x7,%eax
34: 83 c0 03 add $0x3,%eax
37: 38 d0 cmp %dl,%al
39: 7c 08 jl 0x43
3b: 84 d2 test %dl,%dl
3d: 0f .byte 0xf
3e: 85 3a test %edi,(%rdx)


---
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]

Sending this report to the next reporting stage.