Bail out earlier in zend_memnrstr

To avoid decrementing a null pointer lateron. As we need to check
for NULL here anayway, we should take the chance to bail out right
away.

1 files changed, 6 insertions, 4 deletions

diff --git a/Zend/zend_operators.h b/Zend/zend_operators.h
index b126e96611..c6a55c2b6d 100644
--- a/Zend/zend_operators.h
+++ b/Zend/zend_operators.h
@@ -225,10 +225,12 @@ zend_memnrstr(const char *haystack, const char *needle, size_t needle_len, const
 		p -= needle_len;
 
 		do {
-			if ((p = (const char *)zend_memrchr(haystack, *needle, (p - haystack) + 1)) && ne == p[needle_len-1]) {
-				if (!memcmp(needle + 1, p + 1, needle_len - 2)) {
-					return p;
-				}
+			p = (const char *)zend_memrchr(haystack, *needle, (p - haystack) + 1);
+			if (!p) {
+				return NULL;
+			}
+			if (ne == p[needle_len-1] && !memcmp(needle + 1, p + 1, needle_len - 2)) {
+				return p;
 			}
 		} while (p-- >= haystack);