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Author: Girgias

ext/standard/string.c

@@ -2138,6 +2138,12 @@ static zend_string *php_chunk_split(const char *src, size_t srclen, const char *
 	chunks = srclen / chunklen;
 	restlen = srclen - chunks * chunklen; /* srclen % chunklen */
 
+	/*
+	 * chunks+1 cannot overflow as ZEND_LONG_MAX, which is smaller than SIZE_MAX (due to signedness).
+	 * 		This holds if sizeof(zend_long) == sizeof(size_t) which is not true on x32.
+	 * 		As such an overflow fatal error is emitted, see chunk_split_variation(1|2)_32bit.phpt
+	 * srclen + 1 can't overflow, because the maximum string length is smaller than SIZE_MAX due to the string header.
+	 */
 	dest = zend_string_safe_alloc(chunks+1, endlen, srclen+1, 0);
 
 	for (p = src, q = ZSTR_VAL(dest); p < (src + srclen - chunklen + 1); ) {