syzbot

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BUG: KCSAN: data-race in _extract_crng / random_ioctl

write to 0xffffffff841ab068 of 8 bytes by task 18457 on cpu 0:
 random_ioctl+0x32d/0x3a0 drivers/char/random.c:1952
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff841ab068 of 8 bytes by task 18458 on cpu 1:
 _extract_crng+0x57/0x2d0 drivers/char/random.c:994
 extract_crng drivers/char/random.c:1016 [inline]
 extract_crng_user drivers/char/random.c:1072 [inline]
 urandom_read_nowarn+0x182/0x340 drivers/char/random.c:1811
 urandom_read+0x42/0x110 drivers/char/random.c:1832
 do_loop_readv_writev fs/read_write.c:761 [inline]
 do_iter_read+0x3b1/0x4b0 fs/read_write.c:803
 vfs_readv fs/read_write.c:921 [inline]
 do_preadv+0x13b/0x230 fs/read_write.c:1013
 __do_sys_preadv fs/read_write.c:1063 [inline]
 __se_sys_preadv fs/read_write.c:1058 [inline]
 __x64_sys_preadv+0x54/0x60 fs/read_write.c:1058
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000ffffe63e -> 0x00000000ffffe68b

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 18458 Comm: syz-executor.0 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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