MDEV-5338 XML parser accepts malformed data

mysql-test/r/xml.result

@@ -132,7 +132,7 @@ xb1 xc1
 SELECT extractValue(@xml,'/a//@x[2]');
 extractValue(@xml,'/a//@x[2]')
 xb2 xc2
-SET @xml='<a><b>b1</b><b>b2</b><c><b>c1b1</b><b>c1b2</b></c><c><b>c2b1</c></b></a>';
+SET @xml='<a><b>b1</b><b>b2</b><c><b>c1b1</b><b>c1b2</b></c><c><b>c2b1</b></c></a>';
 SELECT extractValue(@xml,'//b[1]');
 extractValue(@xml,'//b[1]')
 b1 c1b1 c2b1
@@ -1133,3 +1133,22 @@ NULL
 Warnings:
 Warning	1525	Incorrect XML value: 'parse error at line 1 pos 11: STRING unexpected (ident or '/' wanted)'
 End of 5.1 tests
+#
+# Start of 5.3 tests
+#
+#
+# MDEV-5338 XML parser accepts malformed data
+#
+SELECT ExtractValue('<a>xxx</c>','/a/b');
+ExtractValue('<a>xxx</c>','/a/b')
+NULL
+Warnings:
+Warning	1525	Incorrect XML value: 'parse error at line 1 pos 10: '</c>' unexpected ('</a>' wanted)'
+SELECT ExtractValue('<a><b>xxx</c></a>','/a/b');
+ExtractValue('<a><b>xxx</c></a>','/a/b')
+NULL
+Warnings:
+Warning	1525	Incorrect XML value: 'parse error at line 1 pos 13: '</c>' unexpected ('</b>' wanted)'
+#
+# End of 5.3 tests
+#

mysql-test/t/xml.test

@@ -53,7 +53,7 @@ SELECT extractValue(@xml,'/a//@x');
 SELECT extractValue(@xml,'/a//@x[1]');
 SELECT extractValue(@xml,'/a//@x[2]');
 
-SET @xml='<a><b>b1</b><b>b2</b><c><b>c1b1</b><b>c1b2</b></c><c><b>c2b1</c></b></a>';
+SET @xml='<a><b>b1</b><b>b2</b><c><b>c1b1</b><b>c1b2</b></c><c><b>c2b1</b></c></a>';
 SELECT extractValue(@xml,'//b[1]');
 SELECT extractValue(@xml,'/descendant::b[1]');
 
@@ -652,3 +652,17 @@ SELECT UPDATEXML(CONVERT(_latin1'<!--' USING utf8),'1','1');
 SELECT ExtractValue(CONVERT('<\"', BINARY(10)), 1);
 
 --echo End of 5.1 tests
+
+--echo #
+--echo # Start of 5.3 tests
+--echo #
+
+--echo #
+--echo # MDEV-5338 XML parser accepts malformed data
+--echo #
+SELECT ExtractValue('<a>xxx</c>','/a/b');
+SELECT ExtractValue('<a><b>xxx</c></a>','/a/b');
+
+--echo #
+--echo # End of 5.3 tests
+--echo #

strings/xml.c

@@ -240,7 +240,7 @@ static void mstr(char *s,const char *src,size_t l1, size_t l2)
 
 static int my_xml_leave(MY_XML_PARSER *p, const char *str, size_t slen)
 {
-  char *e;
+  char *e, *tag;
   size_t glen;
   char s[32];
   char g[32];
@@ -249,13 +249,14 @@ static int my_xml_leave(MY_XML_PARSER *p, const char *str, size_t slen)
   /* Find previous '/' or beginning */
   for (e=p->attrend; (e>p->attr) && (e[0] != '/') ; e--);
   glen = (size_t) ((e[0] == '/') ? (p->attrend-e-1) : p->attrend-e);
-  
-  if (str && (slen != glen))
+  tag= e[0] == '/' ? e + 1 : e;
+
+  if (str && (slen != glen || memcmp(str, tag, slen)))
   {
     mstr(s,str,sizeof(s)-1,slen);
     if (glen)
     {
-      mstr(g,e+1,sizeof(g)-1,glen),
+      mstr(g, tag, sizeof(g)-1, glen);
       sprintf(p->errstr,"'</%s>' unexpected ('</%s>' wanted)",s,g);
     }
     else