dnsmasq: Fix CVE-2026-4891

Pick patch from [1] dnsmasq 2.90 debian bookworm pacthes.

[1] https://sources.debian.org/src/dnsmasq/2.90-4~deb12u2/debian/patches/CVE-2026-4891.patch

Signed-off-by: Hugo SIMELIERE (Schneider Electric) <hsimeliere.opensource@witekio.com>
Reviewed-by: Bruno VERNAY <bruno.vernay@se.com>
Signed-off-by: Anuj Mittal <anuj.mittal@oss.qualcomm.com>

2 files changed, 45 insertions, 0 deletions

diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb
index 38fa271dc3..0d20e10712 100644
--- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb
+++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb
@@ -16,6 +16,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV
            file://dnsmasq-resolvconf.service \
            file://dnsmasq-noresolvconf.service \
            file://dnsmasq-resolved.conf \
+           file://CVE-2026-4891.patch \
 "
 SRC_URI[sha256sum] = "8f6666b542403b5ee7ccce66ea73a4a51cf19dd49392aaccd37231a2c51b303b"
 
diff --git a/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4891.patch b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4891.patch
new file mode 100644
index 0000000000..b566acb286
--- /dev/null
+++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4891.patch
@@ -0,0 +1,44 @@
+From 046fe2393ea47622b8e1c3e0c6dcca8347a6c431 Mon Sep 17 00:00:00 2001
+From: Simon Kelley <simon@thekelleys.org.uk>
+Date: Wed, 25 Mar 2026 23:04:08 +0000
+Subject: [PATCH] Verify rdlen field in RRSIG packets. CVE-2026-4891
+
+Bug report from Royce M <royce@xchglabs.com>
+
+This avoids crafted packets which give a value for rdlen _less_
+then the space taken up by the fixed data and the signer's name
+and engender a negative calculated length for the signature.
+
+CVE: CVE-2026-4891
+Upstream-Status: Backport [https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=788b4e0f6c05217981b512bed4e5fea6f8855d01]
+
+Signed-off-by: Hugo SIMELIERE (Schneider Electric) <hsimeliere.opensource@witekio.com>
+---
+ src/dnssec.c | 10 +++++++---
+ 1 file changed, 7 insertions(+), 3 deletions(-)
+
+diff --git a/src/dnssec.c b/src/dnssec.c
+index 68f1b5d0..d32db5b4 100644
+--- a/src/dnssec.c
++++ b/src/dnssec.c
+@@ -546,10 +546,14 @@ static int validate_rrset(time_t now, struct dns_header *header, size_t plen, in
+ 
+           *ttl_out = ttl;
+         }
+-       
++
++      /* Don't trust rdlen not to be too small and give us a negative sig_len
++        It has already been checked that it doesn't run us off the end
++        of the packet. */
++      if ((sig_len = rdlen - (p - psav)) <= 0)
++       return STAT_BOGUS;
++
+       sig = p;
+-      sig_len = rdlen - (p - psav);
+-              
+       nsigttl = htonl(orig_ttl);
+       
+       hash->update(ctx, 18, psav);
+-- 
+2.43.0
+