------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 2 PID: 9348 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Modules linked in: CPU: 2 PID: 9348 Comm: kworker/u16:3 Not tainted 5.12.0-rc8-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Workqueue: qrtr_ns_handler qrtr_ns_worker RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Code: 09 31 ff 89 de e8 57 29 ab fd 84 db 0f 85 36 ff ff ff e8 9a 22 ab fd 48 c7 c7 20 db c1 89 c6 05 87 1e e8 09 01 e8 c0 85 f9 04 <0f> 0b e9 17 ff ff ff e8 7b 22 ab fd 0f b6 1d 6c 1e e8 09 31 ff 89 RSP: 0018:ffffc900073079f8 EFLAGS: 00010086 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff88801aad54c0 RSI: ffffffff815c4d25 RDI: fffff52000e60f31 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815bdabe R11: 0000000000000000 R12: ffff888040388000 R13: ffff888025196400 R14: ffff888019571930 R15: ffff888019571934 FS: 0000000000000000(0000) GS:ffff88802cc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000814773c CR3: 0000000069642000 CR4: 0000000000150ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_add include/linux/refcount.h:199 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] qrtr_node_acquire net/qrtr/qrtr.c:201 [inline] qrtr_node_lookup net/qrtr/qrtr.c:397 [inline] qrtr_send_resume_tx net/qrtr/qrtr.c:1009 [inline] qrtr_recvmsg+0x85a/0x990 net/qrtr/qrtr.c:1077 sock_recvmsg_nosec net/socket.c:888 [inline] sock_recvmsg net/socket.c:906 [inline] sock_recvmsg net/socket.c:902 [inline] kernel_recvmsg+0x110/0x160 net/socket.c:931 qrtr_ns_worker+0x15a/0x1710 net/qrtr/ns.c:684 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294