------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 24 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28 Modules linked in: CPU: 1 UID: 0 PID: 24 Comm: ksoftirqd/1 Not tainted 6.12.0-rc6-syzkaller-01249-g774ca6d3bf24 #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: a0 c4 60 8c e8 37 6a 98 fc 90 0f 0b 90 90 eb 99 e8 0b 74 d7 fc c6 05 14 a3 49 0b 01 90 48 c7 c7 00 c5 60 8c e8 17 6a 98 fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 e8 73 d7 fc c6 05 ee a2 49 0b 01 90 RSP: 0018:ffffc900001e74e0 EFLAGS: 00010246 RAX: b49f0fae8794d100 RBX: ffff888033cda864 RCX: ffff88801d2f0000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000003 R08: ffffffff8155d312 R09: fffffbfff1cf9fd0 R10: dffffc0000000000 R11: fffffbfff1cf9fd0 R12: ffff88801d738068 R13: ffff888033cda864 R14: 1ffff11003ae7018 R15: ffff88801d738000 FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000557f98005a28 CR3: 00000000279a6000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: 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_tp_cmd_recv net/can/j1939/transport.c:2113 [inline] j1939_tp_recv+0x7fe/0x1050 net/can/j1939/transport.c:2161 j1939_can_recv+0x732/0xb20 net/can/j1939/main.c:108 deliver net/can/af_can.c:573 [inline] can_rcv_filter+0x359/0x7f0 net/can/af_can.c:607 can_receive+0x327/0x480 net/can/af_can.c:664 can_rcv+0x144/0x260 net/can/af_can.c:688 __netif_receive_skb_one_core net/core/dev.c:5672 [inline] __netif_receive_skb+0x2e0/0x650 net/core/dev.c:5785 process_backlog+0x662/0x15b0 net/core/dev.c:6117 __napi_poll+0xcb/0x490 net/core/dev.c:6838 napi_poll net/core/dev.c:6907 [inline] net_rx_action+0x89b/0x1240 net/core/dev.c:7029 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554 run_ksoftirqd+0xca/0x130 kernel/softirq.c:927 smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164 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