------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 19655 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Modules linked in:
CPU: 3 PID: 19655 Comm: syz-executor.1 Not tainted 5.12.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Code: 09 31 ff 89 de e8 a7 30 b0 fd 84 db 0f 85 36 ff ff ff e8 ba 28 b0 fd 48 c7 c7 60 ad be 89 c6 05 9f 17 ef 09 01 e8 53 57 ff 04 <0f> 0b e9 17 ff ff ff e8 9b 28 b0 fd 0f b6 1d 84 17 ef 09 31 ff 89
RSP: 0018:ffffc90000e57d28 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815bb195 RDI: fffff520001caf97
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815b423e R11: 0000000000000000 R12: ffff88802ae08000
R13: ffff88802ae08000 R14: ffff888064c30568 R15: ffff888020580050
FS:  00007f3a55315700(0000) GS:ffff88802cd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe89feea108 CR3: 0000000068440000 CR4: 0000000000150ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 kref_get include/linux/kref.h:45 [inline]
 j1939_netdev_start+0x777/0x890 net/can/j1939/main.c:271
 j1939_sk_bind+0x9b8/0xe20 net/can/j1939/socket.c:479
 __sys_bind+0x1e9/0x250 net/socket.c:1637
 __do_sys_bind net/socket.c:1648 [inline]
 __se_sys_bind net/socket.c:1646 [inline]
 __x64_sys_bind+0x6f/0xb0 net/socket.c:1646
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x465f69
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3a55315188 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465f69
RDX: 0000000000000018 RSI: 0000000020000200 RDI: 0000000000000003
RBP: 00000000004bfa3f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffc662a78df R14: 00007f3a55315300 R15: 0000000000022000