Prevent segmentation fault

pcre_exec internally calls match function which can recurse a lot
depending on the pattern and the string. We should set a recursion
limit to prevent segmentation faults.

Author: jan-cerny

src/common/util.c

@@ -47,6 +47,7 @@
 #endif
 
 #define PATH_SEPARATOR '/'
+#define OSCAP_PCRE_EXEC_RECURSION_LIMIT 1000
 
 int oscap_string_to_enum(const struct oscap_string_map *map, const char *str)
 {
@@ -366,10 +367,13 @@ int oscap_get_substrings(char *str, int *ofs, pcre *re, int want_substrs, char *
 		ovector[i] = -1;
 	}
 
+	struct pcre_extra extra;
+	extra.match_limit_recursion = OSCAP_PCRE_EXEC_RECURSION_LIMIT;
+	extra.flags = PCRE_EXTRA_MATCH_LIMIT_RECURSION;
 #if defined(OS_SOLARIS)
-	rc = pcre_exec(re, NULL, str, strlen(str), *ofs, PCRE_NO_UTF8_CHECK, ovector, ovector_len);
+	rc = pcre_exec(re, &extra, str, strlen(str), *ofs, PCRE_NO_UTF8_CHECK, ovector, ovector_len);
 #else
-	rc = pcre_exec(re, NULL, str, strlen(str), *ofs, 0, ovector, ovector_len);
+	rc = pcre_exec(re, &extra, str, strlen(str), *ofs, 0, ovector, ovector_len);
 #endif
 
 	if (rc < -1) {