Fix 78213: Empty row pocket

We have to ensure that we don't create an arena which is smaller than
its header, regardless of the configured alignment.

Author: cmb69

NEWS

@@ -21,6 +21,9 @@ PHP                                                                        NEWS
 - LiteSpeed:
   . Updated to LiteSpeed SAPI V7.5 (Fixed clean shutdown). (George Wang)
 
+- MySQLnd:
+  . Fixed bug #78213 (Empty row pocket). (cmb)
+
 - Standard:
   . Fixed bug #69100 (Bus error from stream_copy_to_stream (file -> SSL stream)
     with invalid length). (Nikita)

ext/mysqlnd/mysqlnd_block_alloc.c

@@ -161,7 +161,7 @@ mysqlnd_mempool_create(size_t arena_size)
 	MYSQLND_MEMORY_POOL * ret;
 
 	DBG_ENTER("mysqlnd_mempool_create");
-	arena = mysqlnd_arena_create(MAX(arena_size, sizeof(zend_arena)));
+	arena = mysqlnd_arena_create(MAX(arena_size, ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena))));
 	ret = mysqlnd_arena_alloc(&arena, sizeof(MYSQLND_MEMORY_POOL));
 	ret->arena = arena;
 	ret->last = NULL;