[OE-core][wrynose][PATCH v2 05/10] expat: fix CVE-2026-56410

["Deepak Rathore -X (deeratho - E INFOCHIPS PRIVATE LIMITED at Cisco)" <deeratho@cisco.com>]

From: Deepak Rathore <deeratho@cisco.com>

These patches apply the upstream fixes shown in [1] and [2], as
referenced by [3].

[1] https://github.com/libexpat/libexpat/commit/deeb97f7c88d17a16b0ea2521a13733abc283347
[2] https://github.com/libexpat/libexpat/commit/cee20e91bf14dc7f6d2fc48f0d70d86b2dc3afea
[3] https://nvd.nist.gov/vuln/detail/CVE-2026-56410

Signed-off-by: Deepak Rathore <deeratho@cisco.com>
---
- Changes from v1 to v2:
- Drop the Wrynose-only stdint.h include from CVE-2026-56410_p1.patch
  because current Wrynose already provides it through expat.h via OE-Core
  commit 21042df15008.
- Keep Backport Changes only for the remaining older malloc-cast context
  adjustment.

 .../expat/expat/CVE-2026-56410_p1.patch       | 40 ++++++++++++++++++
 .../expat/expat/CVE-2026-56410_p2.patch       | 41 +++++++++++++++++++
 meta/recipes-core/expat/expat_2.7.5.bb        |  2 +
 3 files changed, 83 insertions(+)
 create mode 100644 meta/recipes-core/expat/expat/CVE-2026-56410_p1.patch
 create mode 100644 meta/recipes-core/expat/expat/CVE-2026-56410_p2.patch

diff --git a/meta/recipes-core/expat/expat/CVE-2026-56410_p1.patch b/meta/recipes-core/expat/expat/CVE-2026-56410_p1.patch
new file mode 100644
index 0000000000..aa4378f1b7
--- /dev/null
+++ b/meta/recipes-core/expat/expat/CVE-2026-56410_p1.patch
@@ -0,0 +1,40 @@
+From 759b77a8439bcbf57c86900bc472d46d8ef70c92 Mon Sep 17 00:00:00 2001
+From: netliomax25-code <netliomax25@gmail.com>
+Date: Fri, 29 May 2026 17:51:25 +0530
+Subject: [PATCH] xmlwf: protect resolveSystemId from integer overflow
+
+CVE: CVE-2026-56410
+Upstream-Status: Backport [https://github.com/libexpat/libexpat/commit/deeb97f7c88d17a16b0ea2521a13733abc283347]
+
+Backport Changes:
+- Adjust the removed allocation line for Wrynose's explicit malloc cast while
+  keeping upstream's overflow checks and final allocation logic.
+
+(cherry picked from commit deeb97f7c88d17a16b0ea2521a13733abc283347)
+Signed-off-by: Deepak Rathore <deeratho@cisco.com>
+---
+ expat/xmlwf/xmlfile.c | 9 +++++++--
+ 1 file changed, 7 insertions(+), 2 deletions(-)
+
+diff --git a/expat/xmlwf/xmlfile.c b/expat/xmlwf/xmlfile.c
+index c4eb839f..31a40209 100644
+--- a/expat/xmlwf/xmlfile.c
++++ b/expat/xmlwf/xmlfile.c
+@@ -138,8 +138,13 @@ resolveSystemId(const XML_Char *base, const XML_Char *systemId,
+ #endif
+   )
+     return systemId;
+-  *toFree = (XML_Char *)malloc((tcslen(base) + tcslen(systemId) + 2)
+-                               * sizeof(XML_Char));
++  const size_t charsRequired = tcslen(base) + tcslen(systemId) + 2;
++
++  /* Detect and prevent integer overflow */
++  if (charsRequired > SIZE_MAX / sizeof(XML_Char))
++    return systemId;
++
++  *toFree = malloc(charsRequired * sizeof(XML_Char));
+   if (! *toFree)
+     return systemId;
+   tcscpy(*toFree, base);
+-- 
+2.43.7
diff --git a/meta/recipes-core/expat/expat/CVE-2026-56410_p2.patch b/meta/recipes-core/expat/expat/CVE-2026-56410_p2.patch
new file mode 100644
index 0000000000..71f3122602
--- /dev/null
+++ b/meta/recipes-core/expat/expat/CVE-2026-56410_p2.patch
@@ -0,0 +1,41 @@
+From f16fa442eaa81bfceec5302d977219959eaac7b7 Mon Sep 17 00:00:00 2001
+From: netliomax25-code <netliomax25@gmail.com>
+Date: Sat, 30 May 2026 11:28:51 +0530
+Subject: [PATCH] xmlwf: guard each operator in resolveSystemId length sum
+
+CVE: CVE-2026-56410
+Upstream-Status: Backport [https://github.com/libexpat/libexpat/commit/cee20e91bf14dc7f6d2fc48f0d70d86b2dc3afea]
+
+(cherry picked from commit cee20e91bf14dc7f6d2fc48f0d70d86b2dc3afea)
+Signed-off-by: Deepak Rathore <deeratho@cisco.com>
+---
+ expat/xmlwf/xmlfile.c | 12 ++++++++++--
+ 1 file changed, 10 insertions(+), 2 deletions(-)
+
+diff --git a/expat/xmlwf/xmlfile.c b/expat/xmlwf/xmlfile.c
+index 31a40209..15c69217 100644
+--- a/expat/xmlwf/xmlfile.c
++++ b/expat/xmlwf/xmlfile.c
+@@ -139,9 +139,17 @@ resolveSystemId(const XML_Char *base, const XML_Char *systemId,
+ #endif
+   )
+     return systemId;
+-  const size_t charsRequired = tcslen(base) + tcslen(systemId) + 2;
++  const size_t baseLen = tcslen(base);
++  const size_t systemIdLen = tcslen(systemId);
+ 
+-  /* Detect and prevent integer overflow */
++  /* Detect and prevent integer overflow in the addition (without risking
++     underflow) */
++  if (baseLen > SIZE_MAX - systemIdLen || baseLen > SIZE_MAX - systemIdLen - 2)
++    return systemId;
++
++  const size_t charsRequired = baseLen + systemIdLen + 2;
++
++  /* Detect and prevent integer overflow in the multiplication */
+   if (charsRequired > SIZE_MAX / sizeof(XML_Char))
+     return systemId;
+ 
+-- 
+2.43.7
+
diff --git a/meta/recipes-core/expat/expat_2.7.5.bb b/meta/recipes-core/expat/expat_2.7.5.bb
index 789fd7e077..5c93b15484 100644
--- a/meta/recipes-core/expat/expat_2.7.5.bb
+++ b/meta/recipes-core/expat/expat_2.7.5.bb
@@ -24,6 +24,8 @@ SRC_URI = "${GITHUB_BASE_URI}/download/R_${VERSION_TAG}/expat-${PV}.tar.bz2  \
            file://CVE-2026-56408.patch;striplevel=2 \
            file://CVE-2026-56404.patch;striplevel=2 \
            file://CVE-2026-56405.patch;striplevel=2 \
+           file://CVE-2026-56410_p1.patch;striplevel=2 \
+           file://CVE-2026-56410_p2.patch;striplevel=2 \
            "
 
 GITHUB_BASE_URI = "https://github.com/libexpat/libexpat/releases/"
-- 
2.35.6