==================================================================
BUG: KFENCE: use-after-free read in virtqueue_get_buf_ctx+0x42/0x2150 drivers/virtio/virtio_ring.c:3129

Use-after-free read at 0xffff88823be22048 (in kfence-#16):
 virtqueue_get_buf_ctx+0x42/0x2150 drivers/virtio/virtio_ring.c:3129
 stats_handle_request drivers/virtio/virtio_balloon.c:450 [inline]
 update_balloon_stats_func+0x121/0x300 drivers/virtio/virtio_balloon.c:547
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

kfence-#16: 0xffff88823be22f00-0xffff88823be22fef, size=240, cache=skbuff_head_cache

allocated by task 13198 on cpu 0 at 1787.700554s (0.398917s ago):
 __alloc_skb+0x1d7/0x7a0 net/core/skbuff.c:704
 alloc_skb include/linux/skbuff.h:1384 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline]
 nsim_dev_trap_report_work+0x2b1/0xcb0 drivers/net/netdevsim/dev.c:922
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

freed by task 13198 on cpu 0 at 1787.704288s (0.395347s ago):
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:892 [inline]
 nsim_dev_trap_report_work+0x879/0xcb0 drivers/net/netdevsim/dev.c:922
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 0 UID: 0 PID: 25534 Comm: kworker/0:1 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: events_freezable update_balloon_stats_func
RIP: 0010:virtqueue_get_buf_ctx+0x42/0x2150 drivers/virtio/virtio_ring.c:3129
Code: 48 89 fb 49 bd 00 00 00 00 00 fc ff df e8 26 18 87 fc 4c 8d 73 48 4c 89 f0 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 d5 15 00 00 <45> 8b 36 4c 89 f7 48 c7 c6 e0 de a8 8e e8 0c 1e 87 fc 41 83 fe 01
RSP: 0018:ffffc900110d7960 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88823be22000 RCX: ffff88803a8e8000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff8de1c71f R09: 0000000000000000
R10: fffff5200221aeb8 R11: fffffbfff1bc38e4 R12: 1ffff11004063d32
R13: dffffc0000000000 R14: ffff88823be22048 R15: ffffc900110d7a80
FS:  0000000000000000(0000) GS:ffff888125c42000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88823be22048 CR3: 0000000027530000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 stats_handle_request drivers/virtio/virtio_balloon.c:450 [inline]
 update_balloon_stats_func+0x121/0x300 drivers/virtio/virtio_balloon.c:547
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
==================================================================
----------------
Code disassembly (best guess):
   0:	48 89 fb             	mov    %rdi,%rbx
   3:	49 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%r13
   a:	fc ff df
   d:	e8 26 18 87 fc       	call   0xfc871838
  12:	4c 8d 73 48          	lea    0x48(%rbx),%r14
  16:	4c 89 f0             	mov    %r14,%rax
  19:	48 c1 e8 03          	shr    $0x3,%rax
  1d:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax
  22:	84 c0                	test   %al,%al
  24:	0f 85 d5 15 00 00    	jne    0x15ff
* 2a:	45 8b 36             	mov    (%r14),%r14d <-- trapping instruction
  2d:	4c 89 f7             	mov    %r14,%rdi
  30:	48 c7 c6 e0 de a8 8e 	mov    $0xffffffff8ea8dee0,%rsi
  37:	e8 0c 1e 87 fc       	call   0xfc871e48
  3c:	41 83 fe 01          	cmp    $0x1,%r14d