linux-kernel - [syzbot] [can?] general protection fault in can_rx

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Message-ID: <68f787b1.a70a0220.3bf6c6.0006.GAE@google.com>
Date: Tue, 21 Oct 2025 06:16:33 -0700
From: syzbot <syzbot+7a52d4cc48fa6eae3c86@...kaller.appspotmail.com>
To: linux-can@...r.kernel.org, linux-kernel@...r.kernel.org, 
	mkl@...gutronix.de, socketcan@...tkopp.net, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [can?] general protection fault in can_rx_unregister

Hello,

syzbot found the following issue on:

HEAD commit:    98ac9cc4b445 Merge tag 'f2fs-fix-6.18-rc2' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1732b67c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
dashboard link: https://syzkaller.appspot.com/bug?extid=7a52d4cc48fa6eae3c86
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1c3d2e04d272/disk-98ac9cc4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eccd74106a6c/vmlinux-98ac9cc4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f6ac0e43209c/bzImage-98ac9cc4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7a52d4cc48fa6eae3c86@...kaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
CPU: 0 UID: 0 PID: 4715 Comm: syz.0.9421 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:can_rx_unregister+0x250/0x730 net/can/af_can.c:537
Code: 54 24 20 48 8d 84 24 b8 00 00 00 48 8d 74 24 78 48 8d 78 b0 e8 11 dc ff ff 48 ba 00 00 00 00 00 fc ff df 48 89 c1 48 c1 e9 03 <80> 3c 11 00 0f 85 7a 04 00 00 48 8b 18 44 8b 64 24 68 44 8b 74 24
RSP: 0018:ffffc9000584fba8 EFLAGS: 00010206
RAX: 0000000000000030 RBX: 0000000000000000 RCX: 0000000000000006
RDX: dffffc0000000000 RSI: ffffffff8a56c94b RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 00000000c00007ff
R10: 00000000c00007ff R11: 0000000000000001 R12: ffff88808f3a8568
R13: ffff88807c774000 R14: 0000000000000002 R15: 1ffff92000b09f7c
FS:  000055558d910500(0000) GS:ffff8881249d6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b327dfff8 CR3: 000000005b42d000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 isotp_release+0x937/0xb90 net/can/isotp.c:1213
 __sock_release+0xb3/0x270 net/socket.c:662
 sock_close+0x1c/0x30 net/socket.c:1455
 __fput+0x402/0xb70 fs/file_table.c:468
 task_work_run+0x150/0x240 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x130 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x426/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc323b8efc9
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:00007ffdf923ea98 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fc323de7da0 RCX: 00007fc323b8efc9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fc323de7da0 R08: 00000000000427cc R09: 0000000ff923ed8f
R10: 00007fc323de7cb0 R11: 0000000000000246 R12: 000000000021db0a
R13: 00007fc323de6270 R14: ffffffffffffffff R15: 00007ffdf923ebb0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:can_rx_unregister+0x250/0x730 net/can/af_can.c:537
Code: 54 24 20 48 8d 84 24 b8 00 00 00 48 8d 74 24 78 48 8d 78 b0 e8 11 dc ff ff 48 ba 00 00 00 00 00 fc ff df 48 89 c1 48 c1 e9 03 <80> 3c 11 00 0f 85 7a 04 00 00 48 8b 18 44 8b 64 24 68 44 8b 74 24
RSP: 0018:ffffc9000584fba8 EFLAGS: 00010206
RAX: 0000000000000030 RBX: 0000000000000000 RCX: 0000000000000006
RDX: dffffc0000000000 RSI: ffffffff8a56c94b RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 00000000c00007ff
R10: 00000000c00007ff R11: 0000000000000001 R12: ffff88808f3a8568
R13: ffff88807c774000 R14: 0000000000000002 R15: 1ffff92000b09f7c
FS:  000055558d910500(0000) GS:ffff8881249d6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b327dfff8 CR3: 000000005b42d000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	54                   	push   %rsp
   1:	24 20                	and    $0x20,%al
   3:	48 8d 84 24 b8 00 00 	lea    0xb8(%rsp),%rax
   a:	00
   b:	48 8d 74 24 78       	lea    0x78(%rsp),%rsi
  10:	48 8d 78 b0          	lea    -0x50(%rax),%rdi
  14:	e8 11 dc ff ff       	call   0xffffdc2a
  19:	48 ba 00 00 00 00 00 	movabs $0xdffffc0000000000,%rdx
  20:	fc ff df
  23:	48 89 c1             	mov    %rax,%rcx
  26:	48 c1 e9 03          	shr    $0x3,%rcx
* 2a:	80 3c 11 00          	cmpb   $0x0,(%rcx,%rdx,1) <-- trapping instruction
  2e:	0f 85 7a 04 00 00    	jne    0x4ae
  34:	48 8b 18             	mov    (%rax),%rbx
  37:	44 8b 64 24 68       	mov    0x68(%rsp),%r12d
  3c:	44                   	rex.R
  3d:	8b                   	.byte 0x8b
  3e:	74 24                	je     0x64


---
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