[v6.6] general protection fault in bcsp_recv

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f5b4c104b7d Linux 6.6.95
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13cfd88c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b80883c3ded77c16
dashboard link: https://syzkaller.appspot.com/bug?extid=5d6ea866b1b60f71e271
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0efd4e01816e/disk-3f5b4c10.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7c9d20858cc/vmlinux-3f5b4c10.xz
kernel image: https://storage.googleapis.com/syzbot-assets/18f8dc74ef68/bzImage-3f5b4c10.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5d6ea8...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
CPU: 1 PID: 8105 Comm: syz.1.788 Not tainted 6.6.95-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:bcsp_recv+0x13e/0x1730 drivers/bluetooth/hci_bcsp.c:590
Code: 89 4c 24 40 48 89 54 24 28 48 c1 ea 03 48 89 54 24 68 48 89 5c 24 20 48 c1 eb 03 48 89 5c 24 60 4c 89 7c 24 38 48 8b 44 24 58 <42> 80 3c 30 00 74 08 4c 89 ff e8 93 fa 59 fa 49 8b 1f 31 ff 48 89
RSP: 0018:ffffc90010837c20 EFLAGS: 00010206
RAX: 0000000000000021 RBX: 0000000000000030 RCX: 000000000000002f
RDX: 000000000000002f RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90010837d80 R08: ffff88802a6af41f R09: 1ffff110054d5e83
R10: dffffc0000000000 R11: ffffed10054d5e84 R12: 0000000000000001
R13: ffffc90010837e20 R14: dffffc0000000000 R15: 0000000000000108
FS: 00007fc5571696c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc557168f98 CR3: 000000005b5ed000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
hci_uart_tty_receive+0x188/0x210 drivers/bluetooth/hci_ldisc.c:624
tiocsti+0x23e/0x2c0 drivers/tty/tty_io.c:2291
tty_ioctl+0x62e/0xdd0 drivers/tty/tty_io.c:2693
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc55638e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc557169038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc5565b6080 RCX: 00007fc55638e929
RDX: 0000200000000500 RSI: 0000000000005412 RDI: 0000000000000003
RBP: 00007fc556410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fc5565b6080 R15: 00007ffc1e714518
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bcsp_recv+0x13e/0x1730 drivers/bluetooth/hci_bcsp.c:590
Code: 89 4c 24 40 48 89 54 24 28 48 c1 ea 03 48 89 54 24 68 48 89 5c 24 20 48 c1 eb 03 48 89 5c 24 60 4c 89 7c 24 38 48 8b 44 24 58 <42> 80 3c 30 00 74 08 4c 89 ff e8 93 fa 59 fa 49 8b 1f 31 ff 48 89
RSP: 0018:ffffc90010837c20 EFLAGS: 00010206
RAX: 0000000000000021 RBX: 0000000000000030 RCX: 000000000000002f
RDX: 000000000000002f RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90010837d80 R08: ffff88802a6af41f R09: 1ffff110054d5e83
R10: dffffc0000000000 R11: ffffed10054d5e84 R12: 0000000000000001
R13: ffffc90010837e20 R14: dffffc0000000000 R15: 0000000000000108
FS: 00007fc5571696c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c370005 CR3: 000000005b5ed000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 89 4c 24 40 mov %ecx,0x40(%rsp)
4: 48 89 54 24 28 mov %rdx,0x28(%rsp)
9: 48 c1 ea 03 shr $0x3,%rdx
d: 48 89 54 24 68 mov %rdx,0x68(%rsp)
12: 48 89 5c 24 20 mov %rbx,0x20(%rsp)
17: 48 c1 eb 03 shr $0x3,%rbx
1b: 48 89 5c 24 60 mov %rbx,0x60(%rsp)
20: 4c 89 7c 24 38 mov %r15,0x38(%rsp)
25: 48 8b 44 24 58 mov 0x58(%rsp),%rax
* 2a: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 ff mov %r15,%rdi
34: e8 93 fa 59 fa call 0xfa59facc
39: 49 8b 1f mov (%r15),%rbx
3c: 31 ff xor %edi,%edi
3e: 48 rex.W
3f: 89 .byte 0x89


---
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]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.