Re: [syzbot] [bluetooth?] general protection fault in l2cap_publish_rx_avail

[syzbot <syzbot+49092daf3dd0a57f9e73@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    2ccbdf43d5e7 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=175822fa980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b8786f381e62940f
dashboard link: https://syzkaller.appspot.com/bug?extid=49092daf3dd0a57f9e73
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=164f8251980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10b077ee980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-2ccbdf43.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c40c1cd990d2/vmlinux-2ccbdf43.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a2a94050804e/bzImage-2ccbdf43.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+49092daf3dd0a57f9e73@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: 0 PID: 5191 Comm: kworker/u33:2 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: hci0 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:ffffc900032d7978 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88802a115000 RCX: ffffffff88bb942d
RDX: 000000000000002e RSI: ffffffff89e760be RDI: 0000000000000174
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000003 R12: ffff88802a114000
R13: ffff8880118868c0 R14: ffff88802a11502e R15: ffff8880118868c0
FS:  0000000000000000(0000) GS:ffff88806b000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555926f16c8 CR3: 0000000022a3c000 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+0x20cb/0xa190 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+0x9fb/0x1b60 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:ffffc900032d7978 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88802a115000 RCX: ffffffff88bb942d
RDX: 000000000000002e RSI: ffffffff89e760be RDI: 0000000000000174
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000003 R12: ffff88802a114000
R13: ffff8880118868c0 R14: ffff88802a11502e R15: ffff8880118868c0
FS:  0000000000000000(0000) GS:ffff88806b100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f51d7775348 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)


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