dnsmasq: fix CVE-2026-5172

A buffer overflow in dnsmasq’s extract_addresses() function allows
an attacker to trigger a heap out-of-bounds read and crash by
exploiting a malformed DNS response, enabling extract_name()
to advance the pointer past the record’s end.

Reference:
[ https://nvd.nist.gov/vuln/detail/CVE-2026-5172 ]

Signed-off-by: Abhishek Bachiphale <Abhishek.Bachiphale@windriver.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

2 files changed, 35 insertions, 0 deletions

diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb
index 4ae650f7e7..c19467aed9 100644
--- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb
+++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb
@@ -20,6 +20,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV
            file://CVE-2026-4891.patch \
            file://CVE-2026-4892.patch \
            file://CVE-2026-4893.patch \
+           file://CVE-2026-5172.patch \
 "
 SRC_URI[sha256sum] = "fd908e79ff37f73234afcb6d3363f78353e768703d92abd8e3220ade6819b1e1"
 
diff --git a/meta-networking/recipes-support/dnsmasq/files/CVE-2026-5172.patch b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-5172.patch
new file mode 100644
index 0000000000..ce6e0f464b
--- /dev/null
+++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-5172.patch
@@ -0,0 +1,34 @@
+commit fa3c8ddef6712b52f562813317e6a997e1210123
+Author: Simon Kelley <simon@thekelleys.org.uk>
+Date:   Mon Mar 30 16:24:33 2026 +0100
+
+Fix buffer overflow vulnerability in extract_addresses() CVE-2026-5172
+    
+Thanks to Hugo Martinez Ray for spotting this.
+    
+The value of rdlen for an RR can be a lie, allowing the
+call to extract_name() at rfc1025.c:952 to advance the value of p1
+past the calculated end of the record. The makes the calculation
+of bytes remaining in the RR underflow to a huge number and results
+in a massive heap OOB read and certain crash.
+
+CVE: CVE-2026-5172
+
+Upstream-Status: Backport [ https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=073082ddc0aba7b8efa15a688d6183463b65effa ]
+
+Signed-off-by: Abhishek Bachiphale <Abhishek.Bachiphale@windriver.com>
+
+diff --git a/src/rfc1035.c b/src/rfc1035.c
+index f0e1082..7e05fb5 100644
+--- a/src/rfc1035.c
++++ b/src/rfc1035.c
+@@ -943,7 +943,8 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
+                              /* Name, extract it then re-encode. */
+                              int len;
+                              
+-                             if (!extract_name(header, qlen, &p1, name, EXTR_NAME_EXTRACT, 0))
++                             /* rdlen may lie, and extract_name() advances p1 past where it says the record ends. */
++                             if (!extract_name(header, qlen, &p1, name, EXTR_NAME_EXTRACT, 0) || (p1 > endrr))
+                                {
+                                  blockdata_free(addr.rrblock.rrdata);
+                                  return 2;