------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 21 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.10.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 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 71 ba fd 84 db 0f 85 36 ff ff ff e8 7a 79 ba fd 48 c7 c7 c0 2a 9d 89 c6 05 04 04 23 09 01 e8 4e c3 f5 04 <0f> 0b e9 17 ff ff ff e8 5b 79 ba fd 0f b6 1d e9 03 23 09 31 ff 89 RSP: 0018:ffffc90000dbf9f8 EFLAGS: 00010086 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888010e13480 RSI: ffffffff8158d0a5 RDI: fffff520001b7f31 RBP: 0000000000000002 R08: 0000000000000001 R09: ffff8880b9e2005b R10: 0000000000000000 R11: 0000000000000000 R12: ffff888011170000 R13: ffff888020ac6000 R14: ffff88802be32b70 R15: ffff88802be32b74 FS: 0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000400200 CR3: 0000000022408000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_add include/linux/refcount.h:215 [inline] __refcount_inc include/linux/refcount.h:262 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] qrtr_node_acquire net/qrtr/qrtr.c:196 [inline] qrtr_node_lookup net/qrtr/qrtr.c:389 [inline] qrtr_send_resume_tx net/qrtr/qrtr.c:981 [inline] qrtr_recvmsg+0x845/0x970 net/qrtr/qrtr.c:1044 sock_recvmsg_nosec net/socket.c:885 [inline] sock_recvmsg net/socket.c:903 [inline] sock_recvmsg net/socket.c:899 [inline] kernel_recvmsg+0x110/0x160 net/socket.c:928 qrtr_ns_worker+0x15a/0x1740 net/qrtr/ns.c:692 process_one_work+0x933/0x15a0 kernel/workqueue.c:2272 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296