------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 3 PID: 2920 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Modules linked in: CPU: 3 PID: 2920 Comm: kworker/u16:1 Not tainted 5.11.0-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 97 06 b1 fd 84 db 0f 85 36 ff ff ff e8 aa fe b0 fd 48 c7 c7 40 74 be 89 c6 05 65 1c ef 09 01 e8 78 b3 fe 04 <0f> 0b e9 17 ff ff ff e8 8b fe b0 fd 0f b6 1d 4a 1c ef 09 31 ff 89 RSP: 0018:ffffc9000075f9f8 EFLAGS: 00010086 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888012d9e2c0 RSI: ffffffff815be2c5 RDI: fffff520000ebf31 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815b74ae R11: 0000000000000000 R12: ffff88804086a040 R13: ffff888014f92000 R14: ffff8880218bb1b0 R15: ffff8880218bb1b4 FS: 0000000000000000(0000) GS:ffff88802cd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000970004 CR3: 0000000068192000 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:394 [inline] qrtr_send_resume_tx net/qrtr/qrtr.c:1004 [inline] qrtr_recvmsg+0x84a/0x980 net/qrtr/qrtr.c:1067 sock_recvmsg_nosec net/socket.c:886 [inline] sock_recvmsg net/socket.c:904 [inline] sock_recvmsg net/socket.c:900 [inline] kernel_recvmsg+0x110/0x160 net/socket.c:929 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