Fixed bug #39640 (Segfault with "Allowed memory size exhausted")

Author: dstogov

NEWS

@@ -58,6 +58,7 @@ PHP                                                                        NEWS
 - Fixed bug #39652 (Wrong negative results from memeory_get_usage()). (Dmitry)
 - Fixed bug #39648 (Implementation of PHP functions chown() and chgrp() are not
   thread safe). (Ilia, wharmby at uk dot ibm dot com)
+- Fixed bug #39640 (Segfault with "Allowed memory size exhausted"). (Dmitry)
 - Fixed bug #39623 (thread safety fixes on *nix for putenv() & mime_magic).
   (Ilia, wharmby at uk dot ibm dot com)
 - Fixed bug #39621 (str_replace() is not binary safe on strings with equal 

Zend/zend_alloc.c

@@ -438,7 +438,7 @@ static long _mem_block_end_magic = MEM_BLOCK_END_MAGIC;
 
 #else
 
-# define ZEND_MM_VALID_PTR(ptr) 1
+# define ZEND_MM_VALID_PTR(ptr) (ptr != NULL)
 
 # define ZEND_MM_SET_MAGIC(block, val)