expat: fix CVE-2022-25314

In Expat (aka libexpat) before 2.4.5, there is an integer overflow in
copyString.

Backport patch from:
https://github.com/libexpat/libexpat/pull/560/commits/efcb347440ade24b9f1054671e6bd05e60b4cafd

CVE: CVE-2022-25314

(From OE-Core rev: b92c33285c5f886c95a3734e61007b522b62a71f)

Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/expat/expat/CVE-2022-25314.patch

@@ -0,0 +1,32 @@
+From efcb347440ade24b9f1054671e6bd05e60b4cafd Mon Sep 17 00:00:00 2001
+From: Samanta Navarro <ferivoz@riseup.net>
+Date: Tue, 15 Feb 2022 11:56:57 +0000
+Subject: [PATCH] Prevent integer overflow in copyString
+
+The copyString function is only used for encoding string supplied by
+the library user.
+
+Upstream-Status: Backport
+https://github.com/libexpat/libexpat/pull/560/commits/efcb347440ade24b9f1054671e6bd05e60b4cafd
+
+CVE: CVE-2022-25314
+
+Signed-off-by: Steve Sakoman <steve@sakoman.com>
+
+---
+ expat/lib/xmlparse.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lib/xmlparse.c b/lib/xmlparse.c
+index 4b43e613..a39377c2 100644
+--- a/lib/xmlparse.c
++++ b/lib/xmlparse.c
+@@ -7412,7 +7412,7 @@ getElementType(XML_Parser parser, const ENCODING *enc, const char *ptr,
+ 
+ static XML_Char *
+ copyString(const XML_Char *s, const XML_Memory_Handling_Suite *memsuite) {
+-  int charsRequired = 0;
++  size_t charsRequired = 0;
+   XML_Char *result;
+ 
+   /* First determine how long the string is */

meta/recipes-core/expat/expat_2.2.9.bb

@@ -17,6 +17,7 @@ SRC_URI = "git://github.com/libexpat/libexpat.git;protocol=https;branch=master \
            file://CVE-2022-25236.patch \
            file://CVE-2022-25313.patch \
            file://CVE-2022-25313-regression.patch \
+           file://CVE-2022-25314.patch \
            file://libtool-tag.patch \
          "