==================================================================
BUG: KCSAN: data-race in detach_buf_split / virtqueue_add

read to 0xffff888101b5b92c of 4 bytes by task 7976 on cpu 0:
 virtqueue_add_split drivers/virtio/virtio_ring.c:575 [inline]
 virtqueue_add+0x75a/0x20e0 drivers/virtio/virtio_ring.c:2133
 virtqueue_add_inbuf+0x53/0x80 drivers/virtio/virtio_ring.c:2212
 request_entropy drivers/char/hw_random/virtio-rng.c:61 [inline]
 copy_data drivers/char/hw_random/virtio-rng.c:74 [inline]
 virtio_read+0x1c5/0x3f0 drivers/char/hw_random/virtio-rng.c:92
 rng_get_data drivers/char/hw_random/core.c:197 [inline]
 rng_dev_read+0x1a7/0x5e0 drivers/char/hw_random/core.c:234
 vfs_read+0x19e/0x580 fs/read_write.c:468
 ksys_read+0xeb/0x1a0 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:621
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read-write to 0xffff888101b5b92c of 4 bytes by interrupt on cpu 1:
 detach_buf_split+0x316/0x570 drivers/virtio/virtio_ring.c:760
 virtqueue_get_buf_ctx_split drivers/virtio/virtio_ring.c:835 [inline]
 virtqueue_get_buf_ctx+0x3c2/0x5b0 drivers/virtio/virtio_ring.c:2327
 virtqueue_get_buf+0x1f/0x30 drivers/virtio/virtio_ring.c:2333
 random_recv_done+0x4c/0x90 drivers/char/hw_random/virtio-rng.c:42
 vring_interrupt+0x150/0x170 drivers/virtio/virtio_ring.c:2501
 __handle_irq_event_percpu+0x91/0x490 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x64/0xf0 kernel/irq/handle.c:210
 handle_edge_irq+0x167/0x590 kernel/irq/chip.c:819
 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
 handle_irq arch/x86/kernel/irq.c:231 [inline]
 __common_interrupt+0x3c/0xb0 arch/x86/kernel/irq.c:250
 common_interrupt+0x7a/0x90 arch/x86/kernel/irq.c:240
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636
 check_kcov_mode kernel/kcov.c:175 [inline]
 __sanitizer_cov_trace_pc+0x36/0x60 kernel/kcov.c:207
 arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
 page_fixed_fake_head include/linux/page-flags.h:208 [inline]
 _compound_head include/linux/page-flags.h:249 [inline]
 PageSwapBacked include/linux/page-flags.h:493 [inline]
 mm_counter_file include/linux/mm.h:2493 [inline]
 mm_counter include/linux/mm.h:2502 [inline]
 zap_pte_range mm/memory.c:1433 [inline]
 zap_pmd_range mm/memory.c:1563 [inline]
 zap_pud_range mm/memory.c:1592 [inline]
 zap_p4d_range mm/memory.c:1613 [inline]
 unmap_page_range+0xd7d/0x1e60 mm/memory.c:1634
 unmap_single_vma+0x142/0x1d0 mm/memory.c:1680
 unmap_vmas+0x157/0x200 mm/memory.c:1719
 exit_mmap+0x15b/0x5e0 mm/mmap.c:3111
 __mmput+0x28/0x1c0 kernel/fork.c:1351
 mmput+0x49/0x60 kernel/fork.c:1373
 exit_mm+0xe4/0x180 kernel/exit.c:567
 do_exit+0x580/0x1670 kernel/exit.c:861
 do_group_exit+0x101/0x150 kernel/exit.c:1024
 get_signal+0xeb7/0xff0 kernel/signal.c:2876
 arch_do_signal_or_restart+0x89/0x2a0 arch/x86/kernel/signal.c:306
 exit_to_user_mode_loop+0x6f/0xe0 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x000000ff -> 0x000000fe

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7978 Comm: syz-executor.5 Not tainted 6.4.0-rc5-syzkaller-00305-g022ce8862dff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
==================================================================
virtio_rng virtio3: input:id 1 is not a head!