------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 307 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Modules linked in: CPU: 1 PID: 307 Comm: kworker/u4:5 Not tainted 5.10.0-rc7-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 77 74 b9 fd 84 db 0f 85 36 ff ff ff e8 5a 7c b9 fd 48 c7 c7 00 53 9d 89 c6 05 4d 18 22 09 01 e8 03 eb f5 04 <0f> 0b e9 17 ff ff ff e8 3b 7c b9 fd 0f b6 1d 32 18 22 09 31 ff 89 RSP: 0018:ffffc90001e1f9f8 EFLAGS: 00010086 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888011e03480 RSI: ffffffff8158c835 RDI: fffff520003c3f31 RBP: 0000000000000002 R08: 0000000000000001 R09: ffff8880b9f2011b R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880110c8000 R13: ffff88801b930400 R14: ffff888025e77cb0 R15: ffff888025e77cb4 FS: 0000000000000000(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000778000 CR3: 0000000011ca4000 CR4: 0000000000350ee0 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: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+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296