------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 0 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc5-syzkaller-00219-g1934261d8974 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 d8 8e 0a fd 84 db 0f 85 66 ff ff ff e8 eb 8c 0a fd c6 05 77 20 7a 0b 01 90 48 c7 c7 60 23 b0 8b e8 67 45 cd fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 c8 8c 0a fd 0f b6 1d 52 20 7a 0b 31
RSP: 0018:ffffc90000007bf8 EFLAGS: 00010086
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff814dd3f9
RDX: ffffffff8da957c0 RSI: ffffffff814dd406 RDI: 0000000000000001
RBP: ffff8880664e1108 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880664e1108
R13: ffff88806644fc00 R14: 0000000000000015 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88802b600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f7f455b8 CR3: 000000004b0c8000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __refcount_sub_and_test include/linux/refcount.h:275 [inline]
 __refcount_dec_and_test include/linux/refcount.h:307 [inline]
 refcount_dec_and_test include/linux/refcount.h:325 [inline]
 p9_req_put+0x1ec/0x250 net/9p/client.c:404
 req_done+0x1e7/0x2f0 net/9p/trans_virtio.c:147
 vring_interrupt drivers/virtio/virtio_ring.c:2595 [inline]
 vring_interrupt+0x31b/0x400 drivers/virtio/virtio_ring.c:2570
 __handle_irq_event_percpu+0x229/0x7c0 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
 handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
 handle_irq arch/x86/kernel/irq.c:247 [inline]
 call_irq_handler arch/x86/kernel/irq.c:259 [inline]
 __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:285
 common_interrupt+0x52/0xd0 arch/x86/kernel/irq.c:278
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
RIP: 0010:handle_softirqs+0x1da/0x8f0 kernel/softirq.c:540
Code: 89 44 24 18 48 89 6c 24 10 48 c7 c7 00 70 4b 8b e8 ab 60 b8 09 65 66 c7 05 49 13 b4 7e 00 00 e8 4c 99 42 00 fb bb ff ff ff ff <49> c7 c6 c0 a0 a0 8d 41 0f bc dc 83 c3 01 0f 85 a7 00 00 00 e9 b4
RSP: 0018:ffffc90000007f30 EFLAGS: 00000206
RAX: 000000000082e312 RBX: 00000000ffffffff RCX: 1ffffffff20232e9
RDX: 0000000000000000 RSI: ffffffff8b4cd060 RDI: ffffffff8bb07de0
RBP: ffffffff8da957c0 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff9011db9f R11: 0000000000000000 R12: 0000000000000382
R13: 000000000000000a R14: 0000000000000001 R15: 0000000000000000
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu kernel/softirq.c:637 [inline]
 irq_exit_rcu+0xbb/0x120 kernel/softirq.c:649
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0x95/0xb0 arch/x86/kernel/apic/apic.c:1043
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:92 [inline]
RIP: 0010:default_idle+0xf/0x20 arch/x86/kernel/process.c:743
Code: 4c 01 c7 4c 29 c2 e9 72 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 93 5f 3e 00 fb f4 <fa> c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
RSP: 0018:ffffffff8da07e20 EFLAGS: 00000246
RAX: 000000000082e309 RBX: 0000000000000000 RCX: ffffffff8b081fd9
RDX: 0000000000000000 RSI: ffffffff8b4cd060 RDI: ffffffff8bb07de0
RBP: fffffbfff1b52af8 R08: 0000000000000001 R09: ffffed10056c6fd9
R10: ffff88802b637ecb R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8da957c0 R14: ffffffff9011db98 R15: 0000000000000000
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x32c/0x3f0 kernel/sched/idle.c:326
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:424
 rest_init+0x16b/0x2b0 init/main.c:747
 start_kernel+0x3df/0x4c0 init/main.c:1103
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:488
 common_startup_64+0x13e/0x148
 </TASK>
----------------
Code disassembly (best guess):
   0:	89 44 24 18          	mov    %eax,0x18(%rsp)
   4:	48 89 6c 24 10       	mov    %rbp,0x10(%rsp)
   9:	48 c7 c7 00 70 4b 8b 	mov    $0xffffffff8b4b7000,%rdi
  10:	e8 ab 60 b8 09       	call   0x9b860c0
  15:	65 66 c7 05 49 13 b4 	movw   $0x0,%gs:0x7eb41349(%rip)        # 0x7eb41368
  1c:	7e 00 00
  1f:	e8 4c 99 42 00       	call   0x429970
  24:	fb                   	sti
  25:	bb ff ff ff ff       	mov    $0xffffffff,%ebx
* 2a:	49 c7 c6 c0 a0 a0 8d 	mov    $0xffffffff8da0a0c0,%r14 <-- trapping instruction
  31:	41 0f bc dc          	bsf    %r12d,%ebx
  35:	83 c3 01             	add    $0x1,%ebx
  38:	0f 85 a7 00 00 00    	jne    0xe5
  3e:	e9                   	.byte 0xe9
  3f:	b4                   	.byte 0xb4