------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 7770 at lib/refcount.c:28 refcount_warn_saturate+0x1c8/0x20c lib/refcount.c:28 Modules linked in: CPU: 0 UID: 0 PID: 7770 Comm: kworker/u8:9 Not tainted 6.12.0-rc1-syzkaller-g80cb3fb61135 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 Workqueue: netns cleanup_net pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : refcount_warn_saturate+0x1c8/0x20c lib/refcount.c:28 lr : refcount_warn_saturate+0x1c8/0x20c lib/refcount.c:28 sp : ffff8000800076f0 x29: ffff8000800076f0 x28: dfff800000000000 x27: ffff0000ed1484a4 x26: ffff0000ed1483c0 x25: 00000000000006f9 x24: 0000000000000000 x23: ffff0000ed1484a4 x22: ffff80008a586bd8 x21: 0000000000000003 x20: ffff0000ed1484a4 x19: ffff800092a80000 x18: 0000000000000008 x17: 0000000000000000 x16: ffff8000830b4c50 x15: 0000000000000001 x14: 1fffe000366c78e2 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000103 x10: 0000000000ff0100 x9 : 733ef65bd2296a00 x8 : 733ef65bd2296a00 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff800080006e18 x4 : ffff80008f8dcac0 x3 : ffff800080626e34 x2 : 0000000000000001 x1 : 0000000100000101 x0 : 0000000000000000 Call trace: refcount_warn_saturate+0x1c8/0x20c lib/refcount.c:28 __refcount_sub_and_test include/linux/refcount.h:275 [inline] __refcount_dec_and_test include/linux/refcount.h:307 [inline] refcount_dec_and_test include/linux/refcount.h:325 [inline] skb_unref include/linux/skbuff.h:1232 [inline] __sk_skb_reason_drop net/core/skbuff.c:1213 [inline] sk_skb_reason_drop+0x210/0x43c net/core/skbuff.c:1241 kfree_skb_reason include/linux/skbuff.h:1262 [inline] kfree_skb include/linux/skbuff.h:1271 [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+0x464/0xafc net/can/j1939/transport.c:1484 j1939_tp_cmd_recv net/can/j1939/transport.c:2089 [inline] j1939_tp_recv+0x730/0xe14 net/can/j1939/transport.c:2161 j1939_can_recv+0x5bc/0x934 net/can/j1939/main.c:108 deliver net/can/af_can.c:572 [inline] can_rcv_filter+0x308/0x714 net/can/af_can.c:606 can_receive+0x328/0x488 net/can/af_can.c:663 can_rcv+0x128/0x240 net/can/af_can.c:687 __netif_receive_skb_one_core net/core/dev.c:5662 [inline] __netif_receive_skb+0x18c/0x3c8 net/core/dev.c:5775 process_backlog+0x640/0x123c net/core/dev.c:6107 __napi_poll+0xb4/0x3fc net/core/dev.c:6771 napi_poll net/core/dev.c:6840 [inline] net_rx_action+0x6a8/0xf4c net/core/dev.c:6962 handle_softirqs+0x2e0/0xbf8 kernel/softirq.c:554 __do_softirq+0x14/0x20 kernel/softirq.c:588 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:889 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:86 do_softirq+0x90/0xf8 kernel/softirq.c:455 __local_bh_enable_ip+0x288/0x44c kernel/softirq.c:382 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline] _raw_spin_unlock_bh+0x3c/0x4c kernel/locking/spinlock.c:210 spin_unlock_bh include/linux/spinlock.h:396 [inline] netif_addr_unlock_bh include/linux/netdevice.h:4522 [inline] ieee80211_do_stop+0x550/0x1da4 net/mac80211/iface.c:535 ieee80211_stop+0x3e0/0x448 net/mac80211/iface.c:780 __dev_close_many+0x2d8/0x3c8 net/core/dev.c:1560 dev_close_many+0x1e0/0x474 net/core/dev.c:1585 dev_close+0x174/0x250 net/core/dev.c:1611 cfg80211_shutdown_all_interfaces+0xc0/0x1d8 net/wireless/core.c:280 ieee80211_remove_interfaces+0x10c/0x5dc net/mac80211/iface.c:2273 ieee80211_unregister_hw+0x60/0x29c net/mac80211/main.c:1669 mac80211_hwsim_del_radio+0x220/0x3e4 drivers/net/wireless/virtual/mac80211_hwsim.c:5625 hwsim_exit_net+0x51c/0x5e4 drivers/net/wireless/virtual/mac80211_hwsim.c:6505 ops_exit_list net/core/net_namespace.c:173 [inline] cleanup_net+0x640/0x9b4 net/core/net_namespace.c:626 process_one_work+0x7bc/0x1600 kernel/workqueue.c:3229 process_scheduled_works kernel/workqueue.c:3310 [inline] worker_thread+0x97c/0xeec kernel/workqueue.c:3391 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 irq event stamp: 1404407 hardirqs last enabled at (1404406): [] __up_console_sem kernel/printk/printk.c:344 [inline] hardirqs last enabled at (1404406): [] __console_unlock+0x70/0xc4 kernel/printk/printk.c:2844 hardirqs last disabled at (1404407): [] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:479 softirqs last enabled at (1399908): [] spin_unlock_bh include/linux/spinlock.h:396 [inline] softirqs last enabled at (1399908): [] netif_addr_unlock_bh include/linux/netdevice.h:4522 [inline] softirqs last enabled at (1399908): [] ieee80211_do_stop+0x550/0x1da4 net/mac80211/iface.c:535 softirqs last disabled at (1399909): [] __do_softirq+0x14/0x20 kernel/softirq.c:588 ---[ end trace 0000000000000000 ]--- vcan0: j1939_tp_rxtimer: 0x000000005558b06e: rx timeout, send abort vcan0: j1939_tp_rxtimer: 0x0000000076173a8b: rx timeout, send abort vcan0: j1939_xtp_rx_abort_one: 0x000000005558b06e: 0x00000: (3) A timeout occurred and this is the connection abort to close the session. vcan0: j1939_xtp_rx_abort_one: 0x0000000076173a8b: 0x00000: (3) A timeout occurred and this is the connection abort to close the session.