[v6.6] general protection fault in bnep_session

[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=12dc4982580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b80883c3ded77c16
dashboard link: https://syzkaller.appspot.com/bug?extid=851c709ec37e4e7a19c2
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+851c70...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
CPU: 0 PID: 14878 Comm: kbnepd bnep0 Not tainted 6.6.95-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:klist_put lib/klist.c:212 [inline]
RIP: 0010:klist_del+0x49/0x110 lib/klist.c:230
Code: 33 f7 49 89 dc 49 c1 ec 03 43 80 3c 3c 00 74 08 48 89 df e8 59 fd 8b f7 4c 8b 33 49 83 e6 fe 49 8d 7e 58 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 3b fd 8b f7 49 8b 46 58 48 89 04 24 4c 89
RSP: 0018:ffffc900038978a0 EFLAGS: 00010202
RAX: 000000000000000b RBX: ffff88805d43a460 RCX: ffff888027033c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000058
RBP: ffffc900038979d0 R08: ffff88806aa769b3 R09: 1ffff1100d54ed36
R10: dffffc0000000000 R11: ffffed100d54ed37 R12: 1ffff1100ba8748c
R13: 0000000000000001 R14: 0000000000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555738a6808 CR3: 0000000019ad0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
device_del+0x280/0x900 drivers/base/core.c:3849
unregister_netdevice_many_notify+0x135e/0x1810 net/core/dev.c:11104
unregister_netdevice_many net/core/dev.c:11130 [inline]
unregister_netdevice_queue net/core/dev.c:11010 [inline]
unregister_netdevice include/linux/netdevice.h:3137 [inline]
unregister_netdev+0x148/0x1b0 net/core/dev.c:11148
bnep_session+0x2903/0x2af0 net/bluetooth/bnep/core.c:525
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:klist_put lib/klist.c:212 [inline]
RIP: 0010:klist_del+0x49/0x110 lib/klist.c:230
Code: 33 f7 49 89 dc 49 c1 ec 03 43 80 3c 3c 00 74 08 48 89 df e8 59 fd 8b f7 4c 8b 33 49 83 e6 fe 49 8d 7e 58 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 3b fd 8b f7 49 8b 46 58 48 89 04 24 4c 89
RSP: 0018:ffffc900038978a0 EFLAGS: 00010202
RAX: 000000000000000b RBX: ffff88805d43a460 RCX: ffff888027033c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000058
RBP: ffffc900038979d0 R08: ffff88806aa769b3 R09: 1ffff1100d54ed36
R10: dffffc0000000000 R11: ffffed100d54ed37 R12: 1ffff1100ba8748c
R13: 0000000000000001 R14: 0000000000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555738a6808 CR3: 0000000024af4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 33 f7 xor %edi,%esi
2: 49 89 dc mov %rbx,%r12
5: 49 c1 ec 03 shr $0x3,%r12
9: 43 80 3c 3c 00 cmpb $0x0,(%r12,%r15,1)
e: 74 08 je 0x18
10: 48 89 df mov %rbx,%rdi
13: e8 59 fd 8b f7 call 0xf78bfd71
18: 4c 8b 33 mov (%rbx),%r14
1b: 49 83 e6 fe and $0xfffffffffffffffe,%r14
1f: 49 8d 7e 58 lea 0x58(%r14),%rdi
23: 48 89 f8 mov %rdi,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) <-- trapping instruction
2f: 74 05 je 0x36
31: e8 3b fd 8b f7 call 0xf78bfd71
36: 49 8b 46 58 mov 0x58(%r14),%rax
3a: 48 89 04 24 mov %rax,(%rsp)
3e: 4c rex.WR
3f: 89 .byte 0x89


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[syzbot]

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