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BUG: KCSAN: data-race in fcrypt_decrypt / fcrypt_decrypt

write to 0xffff88802ae55f9b of 8 bytes by task 12445 on cpu 1:
 fcrypt_decrypt+0x446/0x460 crypto/fcrypt.c:294
 cipher_crypt_one crypto/cipher.c:76 [inline]
 crypto_cipher_decrypt_one+0x9e/0x120 crypto/cipher.c:90
 crypto_pcbc_decrypt_segment crypto/pcbc.c:98 [inline]
 crypto_pcbc_decrypt+0xd1/0x1e0 crypto/pcbc.c:146
 crypto_skcipher_decrypt+0x59/0x70 crypto/skcipher.c:647
 _skcipher_recvmsg crypto/algif_skcipher.c:138 [inline]
 skcipher_recvmsg+0x61f/0x7f0 crypto/algif_skcipher.c:157
 ____sys_recvmsg+0x15d/0x310 include/linux/uio.h:234
 ___sys_recvmsg net/socket.c:2611 [inline]
 __sys_recvmsg+0x1d2/0x3a0 net/socket.c:2641
 __do_sys_recvmsg net/socket.c:2651 [inline]
 __se_sys_recvmsg net/socket.c:2648 [inline]
 __x64_sys_recvmsg+0x42/0x50 net/socket.c:2648
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff88802ae55f9b of 8 bytes by task 12450 on cpu 0:
 fcrypt_decrypt+0x446/0x460 crypto/fcrypt.c:294
 cipher_crypt_one crypto/cipher.c:76 [inline]
 crypto_cipher_decrypt_one+0x9e/0x120 crypto/cipher.c:90
 crypto_pcbc_decrypt_segment crypto/pcbc.c:98 [inline]
 crypto_pcbc_decrypt+0xd1/0x1e0 crypto/pcbc.c:146
 crypto_skcipher_decrypt+0x59/0x70 crypto/skcipher.c:647
 _skcipher_recvmsg crypto/algif_skcipher.c:138 [inline]
 skcipher_recvmsg+0x61f/0x7f0 crypto/algif_skcipher.c:157
 ____sys_recvmsg+0x15d/0x310 include/linux/uio.h:234
 ___sys_recvmsg net/socket.c:2611 [inline]
 __sys_recvmsg+0x1d2/0x3a0 net/socket.c:2641
 __do_sys_recvmsg net/socket.c:2651 [inline]
 __se_sys_recvmsg net/socket.c:2648 [inline]
 __x64_sys_recvmsg+0x42/0x50 net/socket.c:2648
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12450 Comm: syz-executor.0 Tainted: G        W         5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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