libxml2: patch security issues

Fixes
CVE-2019-19956
CVE-2020-24977
CVE-2019-20388
CVE-2020-7595

Signed-off-by: Jan Pavlinec <jan.pavlinec@nic.cz>

libs/libxml2/patches/CVE-2019-20388.patch

@@ -0,0 +1,33 @@
+From 6088a74bcf7d0c42e24cff4594d804e1d3c9fbca Mon Sep 17 00:00:00 2001
+From: Zhipeng Xie <xiezhipeng1@huawei.com>
+Date: Tue, 20 Aug 2019 16:33:06 +0800
+Subject: [PATCH] Fix memory leak in xmlSchemaValidateStream
+
+When ctxt->schema is NULL, xmlSchemaSAXPlug->xmlSchemaPreRun
+alloc a new schema for ctxt->schema and set vctxt->xsiAssemble
+to 1. Then xmlSchemaVStart->xmlSchemaPreRun initialize
+vctxt->xsiAssemble to 0 again which cause the alloced schema
+can not be freed anymore.
+
+Found with libFuzzer.
+
+Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
+---
+ xmlschemas.c | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/xmlschemas.c b/xmlschemas.c
+index 301c84499..39d92182f 100644
+--- a/xmlschemas.c
++++ b/xmlschemas.c
+@@ -28090,7 +28090,6 @@ xmlSchemaPreRun(xmlSchemaValidCtxtPtr vctxt) {
+     vctxt->nberrors = 0;
+     vctxt->depth = -1;
+     vctxt->skipDepth = -1;
+-    vctxt->xsiAssemble = 0;
+     vctxt->hasKeyrefs = 0;
+ #ifdef ENABLE_IDC_NODE_TABLES_TEST
+     vctxt->createIDCNodeTables = 1;
+-- 
+GitLab
+