[v6.1] general protection fault in bnep_session (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fdb6fcb41cc7 Linux 6.1.176
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16aa0a1e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=acfbe65fbce84c0c
dashboard link: https://syzkaller.appspot.com/bug?extid=9f60136e31443ff1a18c
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1609e67fe610/disk-fdb6fcb4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7c9914a35256/vmlinux-fdb6fcb4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/401dd54d7ec6/bzImage-fdb6fcb4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9f6013...@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: 1 PID: 13820 Comm: kbnepd bnep0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:klist_put lib/klist.c:212 [inline]
RIP: 0010:klist_del+0x45/0x110 lib/klist.c:230
Code: 6b f7 49 89 dc 49 c1 ec 03 43 80 3c 3c 00 74 08 48 89 df e8 fd b2 bc 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 df b2 bc f7 49 8b 46 58 48 89 04 24 4c 89
RSP: 0018:ffffc9000375f920 EFLAGS: 00010202
RAX: 000000000000000b RBX: ffff888025393460 RCX: ffff8880259e9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000058
RBP: ffffc9000375fa50 R08: ffff88807b6102bb R09: 1ffff1100f6c2057
R10: dffffc0000000000 R11: ffffed100f6c2058 R12: 1ffff11004a7268c
R13: ffff888058854688 R14: 0000000000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005638b9786c48 CR3: 000000002e4c6000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
device_del+0x2e2/0xa80 drivers/base/core.c:3879
unregister_netdevice_many_notify+0x14b6/0x1990 net/core/dev.c:11051
unregister_netdevice_many net/core/dev.c:11077 [inline]
unregister_netdevice_queue net/core/dev.c:10960 [inline]
unregister_netdevice include/linux/netdevice.h:3075 [inline]
unregister_netdev+0x14c/0x1c0 net/core/dev.c:11095
bnep_session+0x29c8/0x2bb0 net/bluetooth/bnep/core.c:547
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:klist_put lib/klist.c:212 [inline]
RIP: 0010:klist_del+0x45/0x110 lib/klist.c:230
Code: 6b f7 49 89 dc 49 c1 ec 03 43 80 3c 3c 00 74 08 48 89 df e8 fd b2 bc 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 df b2 bc f7 49 8b 46 58 48 89 04 24 4c 89
RSP: 0018:ffffc9000375f920 EFLAGS: 00010202
RAX: 000000000000000b RBX: ffff888025393460 RCX: ffff8880259e9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000058
RBP: ffffc9000375fa50 R08: ffff88807b6102bb R09: 1ffff1100f6c2057
R10: dffffc0000000000 R11: ffffed100f6c2058 R12: 1ffff11004a7268c
R13: ffff888058854688 R14: 0000000000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005638b9786c48 CR3: 000000007e5a5000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 6b f7 49 imul $0x49,%edi,%esi
3: 89 dc mov %ebx,%esp
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 fd b2 bc f7 call 0xf7bcb315
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 df b2 bc f7 call 0xf7bcb315
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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