* Fixed: [Double free when using libxml2 as regex engine #117](https://github.com/clicon/clixon/issues/117)

* added libxml2 support in test_pattern.sh when libxml2 is configured

CHANGELOG.md

@@ -87,6 +87,7 @@ Expected: July 2020
 
 ### Corrected Bugs
 
+* Fixed: [Double free when using libxml2 as regex engine #117](https://github.com/clicon/clixon/issues/117)
 * Fixed: Reading in a yang-spec file exactly the same size as the buffer (1024/2048/4096/...) could leave the buffer not terminated with a 0 byte
 * Fixed: The module `clixon-rfc5277` was always enabled, but should only be enabled when `CLICON_STREAM_DISCOVERY_RFC5277` is enabled.
 

configure

@@ -637,6 +637,7 @@ CPP
 wwwuser
 wwwdir
 enable_optyangs
+with_libxml2
 with_restconf
 SH_SUFFIX
 CLIXON_DEFAULT_CONFIG
@@ -3350,6 +3351,7 @@ test -z "$INSTALL_DATA" && INSTALL_DATA='${INSTALL} -m 644'
 
  # If yes, compile apps/restconf
 
+
 wwwdir=/www-data
 
 wwwuser=www-data

configure.ac

@@ -94,6 +94,7 @@ AC_SUBST(CLIXON_DEFAULT_CONFIG)
 AC_SUBST(LIBS)
 AC_SUBST(SH_SUFFIX)
 AC_SUBST(with_restconf) # If yes, compile apps/restconf
+AC_SUBST(with_libxml2)  
 AC_SUBST(enable_optyangs) 
 AC_SUBST(wwwdir,/www-data)
 AC_SUBST(wwwuser,www-data)

lib/src/clixon_validate.c

@@ -984,7 +984,9 @@ xml_yang_validate_add(clicon_handle h,
 		    goto fail;
 		}
 	    }
-	    if ((ys_cv_validate(h, cv, yt, &reason)) != 1){
+	    if ((ret = ys_cv_validate(h, cv, yt, &reason)) < 0)
+		goto done;
+	    if (ret == 0){
 		if (netconf_bad_element_xml(xret, "application",  yang_argument_get(yt), reason) < 0)
 		    goto done;
 		goto fail;

lib/src/clixon_yang.c

@@ -2827,17 +2827,22 @@ yang_type_cache_free(yang_type_cache *ycache)
 	    switch (ycache->yc_rxmode){
 	    case REGEXP_POSIX:
 		cligen_regex_posix_free(cv_void_get(cv));
-		break;
-	    case REGEXP_LIBXML2:
-		cligen_regex_libxml2_free(cv_void_get(cv));
-		break;
-	    default:
-		break;
-	    }
 		if ((p = cv_void_get(cv)) != NULL){
 		    free(p);
 		    cv_void_set(cv, NULL);
 		}
+		break;
+	    case REGEXP_LIBXML2:
+		cligen_regex_libxml2_free(cv_void_get(cv));
+		/* Note, already freed in libxml2 case */
+		if ((p = cv_void_get(cv)) != NULL){
+		    cv_void_set(cv, NULL);
+		}
+		break;
+	    default:
+		break;
+	    }
+
 	}
 	cvec_free(ycache->yc_regexps);
     }

test/config.sh.in

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 # Generated from autotools
 
-WITH_RESTCONF=@with_restconf@
+WITH_RESTCONF=@with_restconf@ # evhtp, fcgi or ""
+WITH_LIBXML2=@with_libxml2@ # yes or ""
 CXX=@CXX@
+

test/test_pattern.sh

@@ -7,7 +7,6 @@
 # Test strings have been generated by:
 #   https://www.browserling.com/tools/text-from-regex
 # This is an unit test, not a clixon system test
-# See test_regexp.sh for unit regexp tests
 #
 # NOTE: no tests for ' quote in strings
 # NOTE, the following does not match in libxml2 (but in clixon):
@@ -22,8 +21,14 @@ APPNAME=example
 cfg=$dir/pattern.xml
 fyang=$dir/pattern.yang
 
-# Regexp mode: posix or libxml2
+
-: ${regex:=posix}
+regexlist="posix"
+if [ "${WITH_LIBXML2}" = yes ] ; then
+    regexlist="$regexlist libxml2"
+fi
+# Loop over supported regexps. Always run posix, run libxml2 if configured
+for regex in $regexlist; do
+    new "pattern tests for regex:$regex"
     
 cat <<EOF > $cfg
 <clixon-config xmlns="http://clicon.org/config">
@@ -720,7 +725,6 @@ testrun "p$pnr" 0 '<![CDATA01234567890]]>'
 #testrun "p$pnr" 0 '<![CDATA[0123456789]]' # XML parse error
 
 # CLI tests
-
 new "CLI tests for RFC7950 Sec 9.4.7 ex 2 AB"
 expectfn "$clixon_cli -1f $cfg -l o set c rfc2 AB" 0 '^$'
 
@@ -797,6 +801,8 @@ if [ $BE -ne 0 ]; then
     sudo pkill -u root -f clixon_backend
 fi
 
+done # regex
+
 rm -rf $dir
 
 # unset conditional parameters