------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 6134 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 6134 Comm: syz.0.43 Not tainted 6.12.0-syzkaller-00971-g158f238aa69d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Code: 60 d9 60 8c e8 37 2f 97 fc 90 0f 0b 90 90 eb 99 e8 8b 40 d6 fc c6 05 92 91 48 0b 01 90 48 c7 c7 c0 d9 60 8c e8 17 2f 97 fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 68 40 d6 fc c6 05 6c 91 48 0b 01 90
RSP: 0018:ffffc90004fb7870 EFLAGS: 00010246
RAX: a92ffd63abc59600 RBX: ffff888033368364 RCX: 0000000000040000
RDX: ffffc9000f4c3000 RSI: 0000000000009d7c RDI: 0000000000009d7d
RBP: 0000000000000003 R08: ffffffff8155e312 R09: 1ffff110170c519a
R10: dffffc0000000000 R11: ffffed10170c519b R12: ffff88803220e468
R13: ffff888033368364 R14: 1ffff11006441c98 R15: ffff88803220e400
FS:  00007f51039486c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30b1bff8 CR3: 000000007eb32000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 kfree_skb_reason include/linux/skbuff.h:1262 [inline]
 kfree_skb include/linux/skbuff.h:1271 [inline]
 j1939_session_destroy net/can/j1939/transport.c:282 [inline]
 __j1939_session_release net/can/j1939/transport.c:294 [inline]
 kref_put include/linux/kref.h:65 [inline]
 j1939_session_put+0x1ed/0x440 net/can/j1939/transport.c:299
 j1939_sk_queue_drop_all+0x191/0x240 net/can/j1939/socket.c:144
 j1939_sk_netdev_event_netdown+0xed/0x160 net/can/j1939/socket.c:1296
 j1939_netdev_notify+0xe2/0x140 net/can/j1939/main.c:377
 notifier_call_chain+0x1a1/0x3e0 kernel/notifier.c:93
 __dev_notify_flags+0x207/0x400
 dev_change_flags+0xf0/0x1a0 net/core/dev.c:8922
 dev_ifsioc+0x7c8/0xe70 net/core/dev_ioctl.c:526
 dev_ioctl+0x719/0x1340 net/core/dev_ioctl.c:783
 sock_do_ioctl+0x240/0x460 net/socket.c:1223
 sock_ioctl+0x626/0x8e0 net/socket.c:1328
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf7/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5102b7e759
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:00007f5103948038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5102d36208 RCX: 00007f5102b7e759
RDX: 0000000020000080 RSI: 0000000000008914 RDI: 000000000000000a
RBP: 00007f5102bf175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5102d36208 R15: 00007ffdb7b519d8
 </TASK>