------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 3 PID: 5953 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 3 UID: 0 PID: 5953 Comm: kworker/3:0 Not tainted 6.14.0-rc7-syzkaller-00179-gb3ee1e460951 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events drm_fb_helper_damage_work
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 78 19 f5 fc 84 db 0f 85 66 ff ff ff e8 cb 1e f5 fc c6 05 e7 26 86 0b 01 90 48 c7 c7 20 17 d3 8b e8 f7 4c b5 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 a8 1e f5 fc 0f b6 1d c2 26 86 0b 31
RSP: 0018:ffffc90000718d90 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817a2269
RDX: ffff8880122f2440 RSI: ffffffff817a2276 RDI: 0000000000000001
RBP: ffff88803236c118 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000005 R12: ffff88803236c118
R13: ffff88801f838400 R14: 0000000000000014 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88806a900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec38101f98 CR3: 000000002d90c000 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:2715 [inline]
 vring_interrupt+0x31b/0x400 drivers/virtio/virtio_ring.c:2690
 __handle_irq_event_percpu+0x229/0x7d0 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:249 [inline]
 call_irq_handler arch/x86/kernel/irq.c:261 [inline]
 __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:287
 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:280
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
RIP: 0010:iowrite16+0x2e/0x80 lib/iomap.c:214
Code: 55 89 fd 53 48 89 f3 e8 30 b6 f0 fc 48 89 de bf ff ff 03 00 e8 53 b1 f0 fc 48 81 fb ff ff 03 00 76 0f e8 15 b6 f0 fc 66 89 2b <5b> 5d e9 0b b6 f0 fc e8 06 b6 f0 fc 48 89 de bf 00 00 01 00 e8 29
RSP: 0018:ffffc90000aaf640 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffffc900000f9000 RCX: ffffffff84c93c6d
RDX: ffff8880122f2440 RSI: ffffffff84c93c7b RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 000000000003ffff
R10: ffffc900000f9000 R11: 0000000000000004 R12: ffff8880245c2e43
R13: ffff888025113ac0 R14: ffff8881066f3000 R15: ffff8880245c3800
 vp_notify+0x5a/0x80 drivers/virtio/virtio_pci_common.c:55
 virtqueue_notify+0x84/0x110 drivers/virtio/virtio_ring.c:2490
 virtio_gpu_notify drivers/gpu/drm/virtio/virtgpu_vq.c:438 [inline]
 virtio_gpu_notify+0x134/0x170 drivers/gpu/drm/virtio/virtgpu_vq.c:425
 virtio_gpu_resource_flush drivers/gpu/drm/virtio/virtgpu_plane.c:183 [inline]
 virtio_gpu_primary_plane_update+0xe48/0x14d0 drivers/gpu/drm/virtio/virtgpu_plane.c:256
 drm_atomic_helper_commit_planes+0x93a/0x1000 drivers/gpu/drm/drm_atomic_helper.c:2800
 drm_atomic_helper_commit_tail+0x69/0xf0 drivers/gpu/drm/drm_atomic_helper.c:1750
 commit_tail+0x353/0x400 drivers/gpu/drm/drm_atomic_helper.c:1835
 drm_atomic_helper_commit+0x2fd/0x380 drivers/gpu/drm/drm_atomic_helper.c:2073
 drm_atomic_commit+0x232/0x300 drivers/gpu/drm/drm_atomic.c:1518
 drm_atomic_helper_dirtyfb+0x5ff/0x790 drivers/gpu/drm/drm_damage_helper.c:181
 drm_fbdev_shmem_helper_fb_dirty+0x1c9/0x330 drivers/gpu/drm/drm_fbdev_shmem.c:117
 drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:376 [inline]
 drm_fb_helper_damage_work+0x285/0x5e0 drivers/gpu/drm/drm_fb_helper.c:399
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3400
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
----------------
Code disassembly (best guess):
   0:	55                   	push   %rbp
   1:	89 fd                	mov    %edi,%ebp
   3:	53                   	push   %rbx
   4:	48 89 f3             	mov    %rsi,%rbx
   7:	e8 30 b6 f0 fc       	call   0xfcf0b63c
   c:	48 89 de             	mov    %rbx,%rsi
   f:	bf ff ff 03 00       	mov    $0x3ffff,%edi
  14:	e8 53 b1 f0 fc       	call   0xfcf0b16c
  19:	48 81 fb ff ff 03 00 	cmp    $0x3ffff,%rbx
  20:	76 0f                	jbe    0x31
  22:	e8 15 b6 f0 fc       	call   0xfcf0b63c
  27:	66 89 2b             	mov    %bp,(%rbx)
* 2a:	5b                   	pop    %rbx <-- trapping instruction
  2b:	5d                   	pop    %rbp
  2c:	e9 0b b6 f0 fc       	jmp    0xfcf0b63c
  31:	e8 06 b6 f0 fc       	call   0xfcf0b63c
  36:	48 89 de             	mov    %rbx,%rsi
  39:	bf 00 00 01 00       	mov    $0x10000,%edi
  3e:	e8                   	.byte 0xe8
  3f:	29                   	.byte 0x29