------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 118 at lib/refcount.c:25 refcount_warn_saturate+0x13d/0x1a0 lib/refcount.c:25 Modules linked in: CPU: 1 PID: 118 Comm: kworker/u4:3 Not tainted 5.11.0-rc4-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+0x13d/0x1a0 lib/refcount.c:25 Code: c7 a0 88 6d 8a 31 c0 e8 01 3e 61 fd 0f 0b eb a3 e8 48 42 94 fd c6 05 98 dc 77 09 01 48 c7 c7 00 89 6d 8a 31 c0 e8 e3 3d 61 fd <0f> 0b eb 85 e8 2a 42 94 fd c6 05 7b dc 77 09 01 48 c7 c7 60 89 6d RSP: 0018:ffffc900012fee98 EFLAGS: 00010046 RAX: 3a4ed10dc7466500 RBX: 0000000000000002 RCX: ffff888011d2b780 RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000 RBP: 0000000000000002 R08: ffffffff8163be62 R09: ffffed10173a4004 R10: ffffed10173a4004 R11: 0000000000000000 R12: ffff888022a63898 R13: dffffc0000000000 R14: 0000000000000a02 R15: ffff888022a63800 FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004f1ef0 CR3: 00000000123e5000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_add include/linux/refcount.h:201 [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+0xc3/0xd0 net/qrtr/qrtr.c:394 qrtr_send_resume_tx net/qrtr/qrtr.c:1004 [inline] qrtr_recvmsg+0x4e9/0xc00 net/qrtr/qrtr.c:1067 qrtr_ns_worker+0x2d2/0x5ca0 net/qrtr/ns.c:684 process_one_work+0x833/0x10c0 kernel/workqueue.c:2275 worker_thread+0xaa4/0x1460 kernel/workqueue.c:2421 kthread+0x39a/0x3c0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296