------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 4589 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 4589 Comm: kworker/u4:7 Not tainted 5.14.0-rc5-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 e7 32 9f fd 84 db 0f 85 36 ff ff ff e8 9a 2c 9f fd 48 c7 c7 20 71 e3 89 c6 05 35 8b 81 09 01 e8 01 c6 11 05 <0f> 0b e9 17 ff ff ff e8 7b 2c 9f fd 0f b6 1d 1a 8b 81 09 31 ff 89 RSP: 0018:ffffc9000acc7a00 EFLAGS: 00010082 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff8880279554c0 RSI: ffffffff815d85c5 RDI: fffff52001598f32 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815d23fe R11: 0000000000000000 R12: ffff8880151d8000 R13: ffff88802ffde400 R14: ffff88802d76ecb0 R15: ffff88802d76ecb4 FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004e4b40 CR3: 0000000026dfb000 CR4: 00000000001526f0 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:202 [inline] qrtr_node_lookup net/qrtr/qrtr.c:398 [inline] qrtr_send_resume_tx net/qrtr/qrtr.c:999 [inline] qrtr_recvmsg+0x85a/0x990 net/qrtr/qrtr.c:1067 sock_recvmsg_nosec net/socket.c:943 [inline] sock_recvmsg net/socket.c:961 [inline] sock_recvmsg net/socket.c:957 [inline] kernel_recvmsg+0x110/0x160 net/socket.c:986 qrtr_ns_worker+0x15a/0x1720 net/qrtr/ns.c:684 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ---------------- Code disassembly (best guess): 0: 09 31 or %esi,(%rcx) 2: ff 89 de e8 e7 32 decl 0x32e7e8de(%rcx) 8: 9f lahf 9: fd std a: 84 db test %bl,%bl c: 0f 85 36 ff ff ff jne 0xffffff48 12: e8 9a 2c 9f fd callq 0xfd9f2cb1 17: 48 c7 c7 20 71 e3 89 mov $0xffffffff89e37120,%rdi 1e: c6 05 35 8b 81 09 01 movb $0x1,0x9818b35(%rip) # 0x9818b5a 25: e8 01 c6 11 05 callq 0x511c62b 2a: 0f 0b ud2 <-- trapping instruction 2c: e9 17 ff ff ff jmpq 0xffffff48 31: e8 7b 2c 9f fd callq 0xfd9f2cb1 36: 0f b6 1d 1a 8b 81 09 movzbl 0x9818b1a(%rip),%ebx # 0x9818b57 3d: 31 ff xor %edi,%edi 3f: 89 .byte 0x89