==================================================================
BUG: KCSAN: data-race in random_recv_done / virtio_read

read to 0xffff88810194d0ec of 4 bytes by task 4504 on cpu 0:
 copy_data drivers/char/hw_random/virtio-rng.c:70 [inline]
 virtio_read+0xc2/0x440 drivers/char/hw_random/virtio-rng.c:92
 rng_get_data drivers/char/hw_random/core.c:198 [inline]
 rng_dev_read+0x1b4/0x630 drivers/char/hw_random/core.c:235
 do_iter_read+0x2d5/0x760 fs/read_write.c:798
 vfs_readv fs/read_write.c:916 [inline]
 do_preadv+0x159/0x230 fs/read_write.c:1008
 __do_sys_preadv fs/read_write.c:1058 [inline]
 __se_sys_preadv fs/read_write.c:1053 [inline]
 __x64_sys_preadv+0x54/0x60 fs/read_write.c:1053
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff88810194d0ec of 4 bytes by interrupt on cpu 1:
 random_recv_done+0x5e/0x80 drivers/char/hw_random/virtio-rng.c:45
 vring_interrupt+0x14c/0x170 drivers/virtio/virtio_ring.c:2470
 __handle_irq_event_percpu+0x92/0x400 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x60/0xf0 kernel/irq/handle.c:210
 handle_edge_irq+0x17e/0x5a0 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+0x60/0x100 arch/x86/kernel/irq.c:250
 common_interrupt+0x9a/0xc0 arch/x86/kernel/irq.c:240
 asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:640
 __sanitizer_cov_trace_const_cmp4+0x0/0xa0 kernel/kcov.c:299
 ext4_da_get_block_prep+0x46/0x9e0 fs/ext4/inode.c:1849
 __block_write_begin_int+0x33d/0xc50 fs/buffer.c:1991
 __block_write_begin+0x55/0x100 fs/buffer.c:2041
 ext4_da_write_begin+0x309/0x5f0 fs/ext4/inode.c:3006
 generic_perform_write+0x1d4/0x3f0 mm/filemap.c:3753
 ext4_buffered_write_iter+0x235/0x3e0 fs/ext4/file.c:285
 ext4_file_write_iter+0x2c7/0x1170
 call_write_iter include/linux/fs.h:2191 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:584
 ksys_write+0xe8/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000 -> 0x00000040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4477 Comm: syz-executor.4 Not tainted 6.1.0-rc6-syzkaller-00176-g08ad43d554ba-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
==================================================================
virtio_rng virtio3: input:id 0 is not a head!