expat: fix CVE-2021-46143

In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an
integer overflow exists for m_groupSize.

Backport patch from:
https://github.com/libexpat/libexpat/pull/538/commits/85ae9a2d7d0e9358f356b33977b842df8ebaec2b

CVE: CVE-2021-46143
(From OE-Core rev: 41a65d27e4ecdc11977e2944d8af2f51c48f32ec)

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

2 files changed, 44 insertions, 0 deletions

diff --git a/meta/recipes-core/expat/expat/CVE-2021-46143.patch b/meta/recipes-core/expat/expat/CVE-2021-46143.patch
new file mode 100644
index 0000000000..d6bafba0ff
--- /dev/null
+++ b/meta/recipes-core/expat/expat/CVE-2021-46143.patch
@@ -0,0 +1,43 @@
+From 85ae9a2d7d0e9358f356b33977b842df8ebaec2b Mon Sep 17 00:00:00 2001
+From: Sebastian Pipping <sebastian@pipping.org>
+Date: Sat, 25 Dec 2021 20:52:08 +0100
+Subject: [PATCH] lib: Prevent integer overflow on m_groupSize in function
+ doProlog (CVE-2021-46143)
+
+---
+ expat/lib/xmlparse.c | 15 +++++++++++++++
+ 1 file changed, 15 insertions(+)
+
+diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
+index b47c31b0..8f243126 100644
+--- a/lib/xmlparse.c
++++ b/lib/xmlparse.c
+@@ -5046,6 +5046,11 @@ doProlog(XML_Parser parser, const ENCODING *enc, const char *s, const char *end,
+       if (parser->m_prologState.level >= parser->m_groupSize) {
+         if (parser->m_groupSize) {
+           {
++            /* Detect and prevent integer overflow */
++            if (parser->m_groupSize > (unsigned int)(-1) / 2u) {
++              return XML_ERROR_NO_MEMORY;
++            }
++
+             char *const new_connector = (char *)REALLOC(
+                 parser, parser->m_groupConnector, parser->m_groupSize *= 2);
+             if (new_connector == NULL) {
+@@ -5056,6 +5061,16 @@ doProlog(XML_Parser parser, const ENCODING *enc, const char *s, const char *end,
+           }
+ 
+           if (dtd->scaffIndex) {
++            /* Detect and prevent integer overflow.
++             * The preprocessor guard addresses the "always false" warning
++             * from -Wtype-limits on platforms where
++             * sizeof(unsigned int) < sizeof(size_t), e.g. on x86_64. */
++#if UINT_MAX >= SIZE_MAX
++            if (parser->m_groupSize > (size_t)(-1) / sizeof(int)) {
++              return XML_ERROR_NO_MEMORY;
++            }
++#endif
++
+             int *const new_scaff_index = (int *)REALLOC(
+                 parser, dtd->scaffIndex, parser->m_groupSize * sizeof(int));
+             if (new_scaff_index == NULL)
diff --git a/meta/recipes-core/expat/expat_2.2.9.bb b/meta/recipes-core/expat/expat_2.2.9.bb
index a21e59f987..757c18c5fa 100644
--- a/meta/recipes-core/expat/expat_2.2.9.bb
+++ b/meta/recipes-core/expat/expat_2.2.9.bb
@@ -9,6 +9,7 @@ LIC_FILES_CHKSUM = "file://COPYING;md5=5b8620d98e49772d95fc1d291c26aa79"
 SRC_URI = "git://github.com/libexpat/libexpat.git;protocol=https;branch=master \
            file://CVE-2013-0340.patch \
            file://CVE-2021-45960.patch \
+           file://CVE-2021-46143.patch \
            file://CVE-2022-22822-27.patch \
            file://libtool-tag.patch \
          "