expat: fix CVE-2024-45491

An issue was discovered in libexpat before 2.6.3. dtdCopy in xmlparse.c can have an
integer overflow for nDefaultAtts on 32-bit platforms (where UINT_MAX equals SIZE_MAX).

(From OE-Core rev: fb5ca8b9dcb00ff579ee70295b68aecdb3084b38)

Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 40 insertions, 0 deletions

diff --git a/meta/recipes-core/expat/expat/CVE-2024-45491.patch b/meta/recipes-core/expat/expat/CVE-2024-45491.patch
new file mode 100644
index 0000000000..2231722f12
--- /dev/null
+++ b/meta/recipes-core/expat/expat/CVE-2024-45491.patch
@@ -0,0 +1,39 @@
+From 17e29cb8ff58a8356ad8ea363c169e227e93e444 Mon Sep 17 00:00:00 2001
+From: Sebastian Pipping <sebastian@pipping.org>
+Date: Mon, 19 Aug 2024 22:34:13 +0200
+Subject: [PATCH] lib: Detect integer overflow in dtdCopy
+
+Reported by TaiYou
+
+CVE: CVE-2024-45491
+
+Upstream-Status: Backport [https://github.com/libexpat/libexpat/pull/891/commits/8e439a9947e9dc80]
+
+Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
+---
+ lib/xmlparse.c | 10 ++++++++++
+ 1 file changed, 10 insertions(+)
+
+diff --git a/lib/xmlparse.c b/lib/xmlparse.c
+index 6f0440b..adb27e3 100644
+--- a/lib/xmlparse.c
++++ b/lib/xmlparse.c
+@@ -6913,6 +6913,16 @@ dtdCopy(XML_Parser oldParser, DTD *newDtd, const DTD *oldDtd,
+     if (! newE)
+       return 0;
+     if (oldE->nDefaultAtts) {
++      /* Detect and prevent integer overflow.
++       * The preprocessor guard addresses the "always false" warning
++       * from -Wtype-limits on platforms where
++       * sizeof(int) < sizeof(size_t), e.g. on x86_64. */
++#if UINT_MAX >= SIZE_MAX
++      if ((size_t)oldE->nDefaultAtts
++          > ((size_t)(-1) / sizeof(DEFAULT_ATTRIBUTE))) {
++        return 0;
++      }
++#endif
+       newE->defaultAtts
+           = ms->malloc_fcn(oldE->nDefaultAtts * sizeof(DEFAULT_ATTRIBUTE));
+       if (! newE->defaultAtts) {
+--
+2.40.0
diff --git a/meta/recipes-core/expat/expat_2.5.0.bb b/meta/recipes-core/expat/expat_2.5.0.bb
index 24d5c85d74..f670f94685 100644
--- a/meta/recipes-core/expat/expat_2.5.0.bb
+++ b/meta/recipes-core/expat/expat_2.5.0.bb
@@ -26,6 +26,7 @@ SRC_URI = "https://github.com/libexpat/libexpat/releases/download/R_${VERSION_TA
            file://CVE-2024-45490-0002.patch \
            file://CVE-2024-45490-0003.patch \
            file://CVE-2024-45490-0004.patch \
+           file://CVE-2024-45491.patch \
            "
 
 UPSTREAM_CHECK_URI = "https://github.com/libexpat/libexpat/releases/"