------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 55 at lib/refcount.c:25 refcount_warn_saturate+0x13d/0x1a0 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 55 Comm: kworker/u4:2 Not tainted 5.13.0-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+0x13d/0x1a0 lib/refcount.c:25 Code: c7 60 5b 92 8a 31 c0 e8 51 48 4f fd 0f 0b eb a3 e8 a8 fe 82 fd c6 05 8c e2 28 0a 01 48 c7 c7 c0 5b 92 8a 31 c0 e8 33 48 4f fd <0f> 0b eb 85 e8 8a fe 82 fd c6 05 6f e2 28 0a 01 48 c7 c7 20 5c 92 RSP: 0018:ffffc90000f6ee98 EFLAGS: 00010046 RAX: 8d0a807e9cb3d100 RBX: 0000000000000002 RCX: ffff8880161a8000 RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000 RBP: 0000000000000002 R08: ffffffff816552b2 R09: ffffed1017343f24 R10: ffffed1017343f24 R11: 0000000000000000 R12: ffff8880303f3898 R13: 00000000fffffffe R14: 0000000000000a02 R15: ffff8880303f3800 FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32821000 CR3: 000000007dfc3000 CR4: 00000000001506f0 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:202 [inline] qrtr_node_lookup+0xc3/0xd0 net/qrtr/qrtr.c:398 qrtr_send_resume_tx net/qrtr/qrtr.c:995 [inline] qrtr_recvmsg+0x501/0xc20 net/qrtr/qrtr.c:1063 qrtr_ns_worker+0x2d2/0x5ca0 net/qrtr/ns.c:684 process_one_work+0x833/0x10c0 kernel/workqueue.c:2275 worker_thread+0xac1/0x1300 kernel/workqueue.c:2421 kthread+0x39a/0x3c0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294