Re: [syzbot] [bluetooth?] general protection fault in l2cap_sock_recv_cb

[syzbot <syzbot+b7f6f8c9303466e16c8a@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in l2cap_sock_recv_cb

Bluetooth: hci0: command tx timeout
Oops: general protection fault, probably for non-canonical address 0xdffffc000000002e: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000170-0x0000000000000177]
CPU: 0 PID: 4480 Comm: kworker/u9:1 Not tainted 6.10.0-rc1-syzkaller-00267-gcc8ed4d0a848-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: hci0 hci_rx_work
RIP: 0010:l2cap_publish_rx_avail net/bluetooth/l2cap_sock.c:1137 [inline]
RIP: 0010:l2cap_sock_recv_cb+0x1a0/0x520 net/bluetooth/l2cap_sock.c:1515
Code: df 80 3c 03 00 74 08 4c 89 ff e8 bb dd 7b f7 4d 8b 3f 49 8d bf 74 01 00 00 48 89 f8 48 c1 e8 03 49 bd 00 00 00 00 00 fc ff df <42> 0f b6 04 28 84 c0 0f 85 f3 02 00 00 41 8b 9f 74 01 00 00 49 81
RSP: 0018:ffffc9000d37f468 EFLAGS: 00010207
RAX: 000000000000002e RBX: 1ffff11005827494 RCX: ffff88802f763c00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000174
RBP: ffff88802c13a000 R08: ffffffff89459100 R09: 1ffff1100582760c
R10: dffffc0000000000 R11: ffffed100582760d R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888069fbd500 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000040 CR3: 000000001cb4e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 l2cap_conless_channel net/bluetooth/l2cap_core.c:6780 [inline]
 l2cap_recv_frame+0x8b6d/0x10670 net/bluetooth/l2cap_core.c:6833
 hci_acldata_packet net/bluetooth/hci_core.c:3842 [inline]
 hci_rx_work+0x50f/0xca0 net/bluetooth/hci_core.c:4079
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
 worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/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 net/bluetooth/l2cap_sock.c:1137 [inline]
RIP: 0010:l2cap_sock_recv_cb+0x1a0/0x520 net/bluetooth/l2cap_sock.c:1515
Code: df 80 3c 03 00 74 08 4c 89 ff e8 bb dd 7b f7 4d 8b 3f 49 8d bf 74 01 00 00 48 89 f8 48 c1 e8 03 49 bd 00 00 00 00 00 fc ff df <42> 0f b6 04 28 84 c0 0f 85 f3 02 00 00 41 8b 9f 74 01 00 00 49 81
RSP: 0018:ffffc9000d37f468 EFLAGS: 00010207
RAX: 000000000000002e RBX: 1ffff11005827494 RCX: ffff88802f763c00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000174
RBP: ffff88802c13a000 R08: ffffffff89459100 R09: 1ffff1100582760c
R10: dffffc0000000000 R11: ffffed100582760d R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888069fbd500 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feea42b7ffc CR3: 000000007cc74000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	df 80 3c 03 00 74    	filds  0x7400033c(%rax)
   6:	08 4c 89 ff          	or     %cl,-0x1(%rcx,%rcx,4)
   a:	e8 bb dd 7b f7       	call   0xf77bddca
   f:	4d 8b 3f             	mov    (%r15),%r15
  12:	49 8d bf 74 01 00 00 	lea    0x174(%r15),%rdi
  19:	48 89 f8             	mov    %rdi,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	49 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%r13
  27:	fc ff df
* 2a:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 f3 02 00 00    	jne    0x32a
  37:	41 8b 9f 74 01 00 00 	mov    0x174(%r15),%ebx
  3e:	49                   	rex.WB
  3f:	81                   	.byte 0x81


Tested on:

commit:         cc8ed4d0 Merge tag 'drm-fixes-2024-06-01' of https://g..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=115864d6980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=47d282ddffae809f
dashboard link: https://syzkaller.appspot.com/bug?extid=b7f6f8c9303466e16c8a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1106883e980000