Fix a compilation warning introduced by MDEV-11782

log_crypt(): Do not cast byte* to uint32_t*, because it may break strict aliasing rules. Instead, cast in the opposite direction.

Author: dr-m

storage/innobase/log/log0crypt.cc

@@ -120,7 +120,8 @@ log_crypt(byte* buf, ulint size, bool decrypt)
 
 for (const byte* const end = buf + size; buf != end;
  buf += OS_FILE_LOG_BLOCK_SIZE) {
-byte dst[OS_FILE_LOG_BLOCK_SIZE - LOG_CRYPT_HDR_SIZE];
+uint32_t dst[(OS_FILE_LOG_BLOCK_SIZE - LOG_CRYPT_HDR_SIZE)
+ / sizeof(uint32_t)];
 const ulint log_block_no = log_block_get_hdr_no(buf);
 
 /* The log block number is not encrypted. */
@@ -130,8 +131,7 @@ log_crypt(byte* buf, ulint size, bool decrypt)
 #else
 ~(LOG_BLOCK_FLUSH_BIT_MASK >> 24)
 #endif
-& (*reinterpret_cast<uint32_t*>(dst)
- = *reinterpret_cast<const uint32_t*>(
+& (*dst = *reinterpret_cast<const uint32_t*>(
  buf + LOG_BLOCK_HDR_NO));
 #if LOG_BLOCK_HDR_NO + 4 != LOG_CRYPT_HDR_SIZE
 # error "LOG_BLOCK_HDR_NO has been moved; redo log format affected!"
@@ -143,7 +143,8 @@ log_crypt(byte* buf, ulint size, bool decrypt)
 log_block_no));
 
 int rc = encryption_crypt(
-buf + LOG_CRYPT_HDR_SIZE, sizeof dst, dst, &dst_len,
+buf + LOG_CRYPT_HDR_SIZE, sizeof dst,
+reinterpret_cast<byte*>(dst), &dst_len,
 const_cast<byte*>(info.crypt_key.bytes),
 sizeof info.crypt_key,
 reinterpret_cast<byte*>(aes_ctr_iv), sizeof aes_ctr_iv,