Issue python#26798: Coverity complains about potential memcpy() of overlapped regions. It doesn't hurt to use memmove() here. CID 1372514 / CID 1372515. Upstream BLAKE2/BLAKE2#32

Author: tiran

Modules/_blake2/impl/blake2b-ref.c

@@ -334,7 +334,7 @@ int blake2b_final( blake2b_state *S, uint8_t *out, uint8_t outlen )
     blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
     blake2b_compress( S, S->buf );
     S->buflen -= BLAKE2B_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
   }
 
   blake2b_increment_counter( S, S->buflen );

Modules/_blake2/impl/blake2b.c

@@ -371,7 +371,7 @@ int blake2b_final( blake2b_state *S, uint8_t *out, uint8_t outlen )
     blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
     blake2b_compress( S, S->buf );
     S->buflen -= BLAKE2B_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
   }
 
   blake2b_increment_counter( S, S->buflen );

Modules/_blake2/impl/blake2s-ref.c

@@ -325,7 +325,7 @@ int blake2s_final( blake2s_state *S, uint8_t *out, uint8_t outlen )
     blake2s_increment_counter( S, BLAKE2S_BLOCKBYTES );
     blake2s_compress( S, S->buf );
     S->buflen -= BLAKE2S_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
   }
 
   blake2s_increment_counter( S, ( uint32_t )S->buflen );

Modules/_blake2/impl/blake2s.c

@@ -348,7 +348,7 @@ int blake2s_final( blake2s_state *S, uint8_t *out, uint8_t outlen )
     blake2s_increment_counter( S, BLAKE2S_BLOCKBYTES );
     blake2s_compress( S, S->buf );
     S->buflen -= BLAKE2S_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2S_BLOCKBYTES, S->buflen );
   }
 
   blake2s_increment_counter( S, ( uint32_t )S->buflen );