[OE-core][wrynose][PATCH v2 09/10] expat: fix CVE-2026-56407

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

From: Deepak Rathore <deeratho@cisco.com>

This patch applies the upstream fix shown in [1] as referenced by [2].

[1] https://github.com/libexpat/libexpat/commit/30c2fc179ce5d2b1b1bae30bbe0dfddeac894e13
[2] https://nvd.nist.gov/vuln/detail/CVE-2026-56407

Signed-off-by: Deepak Rathore <deeratho@cisco.com>
---
- Changes from v1 to v2: Refresh the patch on top of
latest wrynose branch merged commits.
 .../expat/expat/CVE-2026-56407.patch          | 44 +++++++++++++++++++
 meta/recipes-core/expat/expat_2.7.5.bb        |  1 +
 2 files changed, 45 insertions(+)
 create mode 100644 meta/recipes-core/expat/expat/CVE-2026-56407.patch

diff --git a/meta/recipes-core/expat/expat/CVE-2026-56407.patch b/meta/recipes-core/expat/expat/CVE-2026-56407.patch
new file mode 100644
index 0000000000..5a2a22e017
--- /dev/null
+++ b/meta/recipes-core/expat/expat/CVE-2026-56407.patch
@@ -0,0 +1,44 @@
+From 7216b3584bcfb2d415026d16b8902ee7eacad5ca Mon Sep 17 00:00:00 2001
+From: netliomax25-code <netliomax25@gmail.com>
+Date: Tue, 2 Jun 2026 11:59:01 +0530
+Subject: [PATCH] cap entity textLen against signed integer overflow
+
+CVE: CVE-2026-56407
+Upstream-Status: Backport [https://github.com/libexpat/libexpat/commit/30c2fc179ce5d2b1b1bae30bbe0dfddeac894e13]
+
+(cherry picked from commit 30c2fc179ce5d2b1b1bae30bbe0dfddeac894e13)
+Signed-off-by: Deepak Rathore <deeratho@cisco.com>
+---
+ expat/lib/xmlparse.c | 9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
+index 71fe2c79..8e90fea8 100644
+--- a/expat/lib/xmlparse.c
++++ b/expat/lib/xmlparse.c
+@@ -5684,6 +5684,10 @@ doProlog(XML_Parser parser, const ENCODING *enc, const char *s, const char *end,
+             parser, enc, s + enc->minBytesPerChar, next - enc->minBytesPerChar,
+             XML_ACCOUNT_NONE);
+         if (parser->m_declEntity) {
++          /* Detect and prevent signed integer overflow */
++          if ((size_t)poolLength(&dtd->entityValuePool) > (size_t)INT_MAX) {
++            return XML_ERROR_NO_MEMORY;
++          }
+           parser->m_declEntity->textPtr = poolStart(&dtd->entityValuePool);
+           parser->m_declEntity->textLen
+               = (int)(poolLength(&dtd->entityValuePool));
+@@ -7099,6 +7103,11 @@ storeSelfEntityValue(XML_Parser parser, ENTITY *entity) {
+     return XML_ERROR_NO_MEMORY;
+   }
+ 
++  /* Detect and prevent signed integer overflow */
++  if ((size_t)poolLength(pool) > (size_t)INT_MAX) {
++    poolDiscard(pool);
++    return XML_ERROR_NO_MEMORY;
++  }
+   entity->textPtr = poolStart(pool);
+   entity->textLen = (int)(poolLength(pool));
+   poolFinish(pool);
+-- 
+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 bd6656c6e0..9f519b482e 100644
--- a/meta/recipes-core/expat/expat_2.7.5.bb
+++ b/meta/recipes-core/expat/expat_2.7.5.bb
@@ -30,6 +30,7 @@ SRC_URI = "${GITHUB_BASE_URI}/download/R_${VERSION_TAG}/expat-${PV}.tar.bz2  \
            file://CVE-2026-56406.patch;striplevel=2 \
            file://CVE-2026-56409.patch;striplevel=2 \
            file://CVE-2026-56411.patch;striplevel=2 \
+           file://CVE-2026-56407.patch;striplevel=2 \
            "
 
 GITHUB_BASE_URI = "https://github.com/libexpat/libexpat/releases/"
-- 
2.35.6