------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 14301 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Modules linked in: CPU: 1 UID: 0 PID: 14301 Comm: syz.3.1569 Not tainted 6.12.0-rc1-syzkaller-00046-g7ec462100ef9 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Code: ff 89 de e8 78 1c fe fc 84 db 0f 85 66 ff ff ff e8 8b 1a fe fc c6 05 e0 7e b8 0b 01 90 48 c7 c7 40 4a d1 8b e8 17 03 bf fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 68 1a fe fc 0f b6 1d bb 7e b8 0b 31 RSP: 0018:ffffc90000a18948 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff814e7329 RDX: ffff88802cc2bc00 RSI: ffffffff814e7336 RDI: 0000000000000001 RBP: ffff8880671899a4 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffffffff4068 R12: 0000000000000002 R13: 0000000000000000 R14: ffff8880671899a4 R15: ffff8880635a7319 FS: 00007f6832fde6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f281621fd58 CR3: 0000000069ff2000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __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+0x183/0x1a0 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+0x622/0xf50 net/can/j1939/transport.c:1484 j1939_tp_cmd_recv net/can/j1939/transport.c:2089 [inline] j1939_tp_recv+0x568/0xf50 net/can/j1939/transport.c:2161 j1939_can_recv+0x78f/0xa50 net/can/j1939/main.c:108 deliver net/can/af_can.c:572 [inline] can_rcv_filter+0x2a8/0x900 net/can/af_can.c:606 can_receive+0x320/0x5c0 net/can/af_can.c:663 can_rcv+0x1e2/0x280 net/can/af_can.c:687 __netif_receive_skb_one_core+0x1b1/0x1e0 net/core/dev.c:5662 __netif_receive_skb+0x1d/0x160 net/core/dev.c:5775 process_backlog+0x443/0x15f0 net/core/dev.c:6107 __napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:6771 napi_poll net/core/dev.c:6840 [inline] net_rx_action+0xa92/0x1010 net/core/dev.c:6962 handle_softirqs+0x213/0x8f0 kernel/softirq.c:554 do_softirq kernel/softirq.c:455 [inline] do_softirq+0xb2/0xf0 kernel/softirq.c:442 __local_bh_enable_ip+0x100/0x120 kernel/softirq.c:382 spin_unlock_bh include/linux/spinlock.h:396 [inline] nl80211_netlink_notify net/wireless/nl80211.c:20145 [inline] nl80211_netlink_notify+0x612/0x960 net/wireless/nl80211.c:20096 notifier_call_chain+0xb9/0x410 kernel/notifier.c:93 blocking_notifier_call_chain kernel/notifier.c:388 [inline] blocking_notifier_call_chain+0x69/0xa0 kernel/notifier.c:376 netlink_release+0x183f/0x1ff0 net/netlink/af_netlink.c:787 __sock_release+0xb0/0x270 net/socket.c:658 sock_close+0x1c/0x30 net/socket.c:1426 __fput+0x3f6/0xb60 fs/file_table.c:431 __fput_sync+0x45/0x50 fs/file_table.c:516 __do_sys_close fs/open.c:1565 [inline] __se_sys_close fs/open.c:1550 [inline] __x64_sys_close+0x86/0x100 fs/open.c:1550 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f683357cc8a Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 13 8c 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 73 8c 02 00 8b 44 24 RSP: 002b:00007f6832fdcf90 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 000000000000001d RCX: 00007f683357cc8a RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000c RBP: 000000000000000c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f6833736130 R15: 00007ffdc0800968