------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 9 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28 Modules linked in: CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.10.0-syzkaller-12610-g743ff02152bc #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 Workqueue: mld mld_dad_work RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28 Code: 00 17 40 8c e8 67 97 a5 fc 90 0f 0b 90 90 eb 99 e8 1b 89 e3 fc c6 05 76 7d 31 0b 01 90 48 c7 c7 60 17 40 8c e8 47 97 a5 fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 f8 88 e3 fc c6 05 50 7d 31 0b 01 90 RSP: 0018:ffffc900000076e0 EFLAGS: 00010246 RAX: dd711061a2ce5400 RBX: ffff88802cdac9a4 RCX: ffff8880176d0000 RDX: 0000000080000101 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000003 R08: ffffffff81559432 R09: 1ffff1101724519a R10: dffffc0000000000 R11: ffffed101724519b R12: ffff88802c3acc00 R13: ffff88802cdac9a4 R14: ffff88802c3acc00 R15: ffff888077e96418 FS: 0000000000000000(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000002000f000 CR3: 000000002d58c000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kfree_skb_reason include/linux/skbuff.h:1260 [inline] kfree_skb include/linux/skbuff.h:1269 [inline] j1939_session_skb_drop_old net/can/j1939/transport.c:347 [inline] j1939_xtp_rx_cts_one net/can/j1939/transport.c:1445 [inline] j1939_xtp_rx_cts+0x54f/0xc70 net/can/j1939/transport.c:1484 j1939_tp_cmd_recv net/can/j1939/transport.c:2089 [inline] j1939_tp_recv+0x8ae/0x1050 net/can/j1939/transport.c:2161 j1939_can_recv+0x732/0xb20 net/can/j1939/main.c:108 deliver net/can/af_can.c:572 [inline] can_rcv_filter+0x359/0x7f0 net/can/af_can.c:606 can_receive+0x31c/0x470 net/can/af_can.c:663 can_rcv+0x144/0x260 net/can/af_can.c:687 __netif_receive_skb_one_core net/core/dev.c:5660 [inline] __netif_receive_skb+0x2e0/0x650 net/core/dev.c:5774 process_backlog+0x662/0x15b0 net/core/dev.c:6107 __napi_poll+0xcb/0x490 net/core/dev.c:6771 napi_poll net/core/dev.c:6840 [inline] net_rx_action+0x89b/0x1240 net/core/dev.c:6962 handle_softirqs+0x2c4/0x970 kernel/softirq.c:554 do_softirq+0x11b/0x1e0 kernel/softirq.c:455 __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:908 [inline] __dev_queue_xmit+0x1763/0x3e90 net/core/dev.c:4450 dev_queue_xmit include/linux/netdevice.h:3105 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip6_finish_output2+0xfc2/0x1680 net/ipv6/ip6_output.c:137 ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222 NF_HOOK+0x9e/0x430 include/linux/netfilter.h:314 mld_sendpack+0x843/0xdb0 net/ipv6/mcast.c:1818 mld_dad_work+0x44/0x500 net/ipv6/mcast.c:2259 process_one_work kernel/workqueue.c:3231 [inline] process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312 worker_thread+0x86d/0xd40 kernel/workqueue.c:3390 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244