Re: [syzbot] [wireless?] general protection fault in cfg80211_mlme_deauth

[Qasim Ijaz <qasdev00@gmail.com>]

On Tue, Apr 08, 2025 at 04:53:34AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    0af2f6be1b42 Linux 6.15-rc1
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1284523f980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=66996a2350ef05e0
> dashboard link: https://syzkaller.appspot.com/bug?extid=00778a9a557a2a5e1a33
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13c9eb4c580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=179bbd98580000
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-0af2f6be.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/3fcfb8eefe4d/vmlinux-0af2f6be.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/e06a39be2bd8/bzImage-0af2f6be.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+00778a9a557a2a5e1a33@syzkaller.appspotmail.com
> 
> Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]

I done some analysis and it looks like during cfg80211_conn_work() the 
wdev->conn->params.bssid is NULL, this gets passed to cfg80211_conn_do_work() 
which hits the CFG80211_CONN_ASSOC_FAILED label of the switch statement where 
ether_addr_equal() compares the NULL bssid via ether_addr_equal().

Regards,
Qasim

> CPU: 0 UID: 0 PID: 4854 Comm: kworker/0:3 Not tainted 6.15.0-rc1-syzkaller #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
> Workqueue: events cfg80211_conn_work
> RIP: 0010:ether_addr_equal include/linux/etherdevice.h:355 [inline]
> RIP: 0010:cfg80211_mlme_deauth+0x35a/0x940 net/wireless/mlme.c:514
> Code: 8d 9c 24 b0 00 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 28 84 c0 4c 8b 7c 24 28 0f 85 25 03 00 00 44 8b 23 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 2b 03 00 00 45 8b 37 48 8b 44 24 20 48
> RSP: 0018:ffffc90002cdf180 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff888045820e40 RCX: ffff888000b5c880
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffffc90002cdf268 R08: ffffffff8b8395d8 R09: 0000000000000003
> R10: 0000000000000009 R11: ffff888000b5c880 R12: 0000000000000000
> R13: dffffc0000000000 R14: 0000000000000003 R15: 0000000000000000
> FS:  0000000000000000(0000) GS:ffff88808c596000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f25d8438198 CR3: 000000001f4b4000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  cfg80211_conn_do_work+0x369/0xed0 net/wireless/sme.c:229
>  cfg80211_conn_work+0x2c2/0x530 net/wireless/sme.c:273
>  process_one_work kernel/workqueue.c:3238 [inline]
>  process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319
>  worker_thread+0x870/0xd50 kernel/workqueue.c:3400
>  kthread+0x7b7/0x940 kernel/kthread.c:464
>  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:ether_addr_equal include/linux/etherdevice.h:355 [inline]
> RIP: 0010:cfg80211_mlme_deauth+0x35a/0x940 net/wireless/mlme.c:514
> Code: 8d 9c 24 b0 00 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 28 84 c0 4c 8b 7c 24 28 0f 85 25 03 00 00 44 8b 23 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 2b 03 00 00 45 8b 37 48 8b 44 24 20 48
> RSP: 0018:ffffc90002cdf180 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff888045820e40 RCX: ffff888000b5c880
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffffc90002cdf268 R08: ffffffff8b8395d8 R09: 0000000000000003
> R10: 0000000000000009 R11: ffff888000b5c880 R12: 0000000000000000
> R13: dffffc0000000000 R14: 0000000000000003 R15: 0000000000000000
> FS:  0000000000000000(0000) GS:ffff88808c596000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f25d8438198 CR3: 000000001f4b4000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0:	8d 9c 24 b0 00 00 00 	lea    0xb0(%rsp),%ebx
>    7:	48 89 d8             	mov    %rbx,%rax
>    a:	48 c1 e8 03          	shr    $0x3,%rax
>    e:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax
>   13:	84 c0                	test   %al,%al
>   15:	4c 8b 7c 24 28       	mov    0x28(%rsp),%r15
>   1a:	0f 85 25 03 00 00    	jne    0x345
>   20:	44 8b 23             	mov    (%rbx),%r12d
>   23:	4c 89 f8             	mov    %r15,%rax
>   26:	48 c1 e8 03          	shr    $0x3,%rax
> * 2a:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
>   2f:	84 c0                	test   %al,%al
>   31:	0f 85 2b 03 00 00    	jne    0x362
>   37:	45 8b 37             	mov    (%r15),%r14d
>   3a:	48 8b 44 24 20       	mov    0x20(%rsp),%rax
>   3f:	48                   	rex.W
> 
> 
> ---
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