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

[syzbot <syzbot+4ed6852d4da4606c93da@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    acc4d5ff0b61 Merge tag 'net-6.15-rc0' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=135a6178580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=410c49aba9aeb859
dashboard link: https://syzkaller.appspot.com/bug?extid=4ed6852d4da4606c93da
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=134ec7cf980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13315274580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-acc4d5ff.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aad60517b1c2/vmlinux-acc4d5ff.xz
kernel image: https://storage.googleapis.com/syzbot-assets/27bf64833684/bzImage-acc4d5ff.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4ed6852d4da4606c93da@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
CPU: 1 UID: 0 PID: 5945 Comm: syz-executor103 Not tainted 6.14.0-syzkaller-12456-gacc4d5ff0b61 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:bcsp_recv+0x10a/0x17f0 drivers/bluetooth/hci_bcsp.c:590
Code: 18 48 c1 e8 03 48 01 e8 48 89 04 24 48 8d 83 78 01 00 00 48 89 44 24 28 48 c1 e8 03 48 89 44 24 08 e8 aa ca 5c f9 48 8b 04 24 <80> 38 00 0f 85 d1 12 00 00 4c 8b ab 08 01 00 00 31 ff 4c 89 ee e8
RSP: 0018:ffffc90003467bf0 EFLAGS: 00010293
RAX: dffffc0000000021 RBX: 0000000000000000 RCX: ffffffff885e756a
RDX: ffff888024910000 RSI: ffffffff885e75b6 RDI: 0000000000000005
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffffc90003467d88
R13: ffffc90003467d88 R14: 0000000000000001 R15: ffff88810735a800
FS:  00007ffb5ce256c0(0000) GS:ffff8880d6abb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc59fa2f98 CR3: 0000000024ec0000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 hci_uart_tty_receive+0x251/0x7e0 drivers/bluetooth/hci_ldisc.c:627
 tiocsti drivers/tty/tty_io.c:2299 [inline]
 tty_ioctl+0x57b/0x15f0 drivers/tty/tty_io.c:2716
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ffb5ce97899
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 1f 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffb5ce25168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffb5cf1b418 RCX: 00007ffb5ce97899
RDX: 0000200000000140 RSI: 0000000000005412 RDI: 0000000000000004
RBP: 00007ffb5cf1b410 R08: 00007ffcd6d4fb07 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffb5cf1b41c
R13: 0000000000000010 R14: 00007ffcd6d4fa20 R15: 00007ffcd6d4fb08
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bcsp_recv+0x10a/0x17f0 drivers/bluetooth/hci_bcsp.c:590
Code: 18 48 c1 e8 03 48 01 e8 48 89 04 24 48 8d 83 78 01 00 00 48 89 44 24 28 48 c1 e8 03 48 89 44 24 08 e8 aa ca 5c f9 48 8b 04 24 <80> 38 00 0f 85 d1 12 00 00 4c 8b ab 08 01 00 00 31 ff 4c 89 ee e8
RSP: 0018:ffffc90003467bf0 EFLAGS: 00010293
RAX: dffffc0000000021 RBX: 0000000000000000 RCX: ffffffff885e756a
RDX: ffff888024910000 RSI: ffffffff885e75b6 RDI: 0000000000000005
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffffc90003467d88
R13: ffffc90003467d88 R14: 0000000000000001 R15: ffff88810735a800
FS:  00007ffb5ce256c0(0000) GS:ffff8880d6abb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc59fa2f98 CR3: 0000000024ec0000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	18 48 c1             	sbb    %cl,-0x3f(%rax)
   3:	e8 03 48 01 e8       	call   0xe801480b
   8:	48 89 04 24          	mov    %rax,(%rsp)
   c:	48 8d 83 78 01 00 00 	lea    0x178(%rbx),%rax
  13:	48 89 44 24 28       	mov    %rax,0x28(%rsp)
  18:	48 c1 e8 03          	shr    $0x3,%rax
  1c:	48 89 44 24 08       	mov    %rax,0x8(%rsp)
  21:	e8 aa ca 5c f9       	call   0xf95ccad0
  26:	48 8b 04 24          	mov    (%rsp),%rax
* 2a:	80 38 00             	cmpb   $0x0,(%rax) <-- trapping instruction
  2d:	0f 85 d1 12 00 00    	jne    0x1304
  33:	4c 8b ab 08 01 00 00 	mov    0x108(%rbx),%r13
  3a:	31 ff                	xor    %edi,%edi
  3c:	4c 89 ee             	mov    %r13,%rsi
  3f:	e8                   	.byte 0xe8


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