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[AutoPR- Security] Patch dnsmasq for CVE-2026-4891 [MEDIUM] #224

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[AutoPR- Security] Patch dnsmasq for CVE-2026-4891 [MEDIUM] #224

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42 changes: 42 additions & 0 deletions SPECS/dnsmasq/CVE-2026-4891.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,42 @@
From 2309d38fb51a018d066132bb81a1741b4c5b282f 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.

Signed-off-by: Azure Linux Security Servicing Account <azurelinux-security@microsoft.com>
Upstream-reference: https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=patch;h=788b4e0f6c05217981b512bed4e5fea6f8855d01
---
src/dnssec.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/dnssec.c b/src/dnssec.c
index ed2f53f..bdd48ca 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);
--
2.45.4

6 changes: 5 additions & 1 deletion SPECS/dnsmasq/dnsmasq.spec
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@@ -1,14 +1,15 @@
Summary: DNS proxy with integrated DHCP server
Name: dnsmasq
Version: 2.90
Release: 1%{?dist}
Release: 2%{?dist}
License: GPLv2 or GPLv3
Group: System Environment/Daemons
URL: https://www.thekelleys.org.uk/dnsmasq/
Source0: https://www.thekelleys.org.uk/%{name}/%{name}-%{version}.tar.xz
Vendor: Microsoft Corporation
Distribution: Azure Linux
Patch0: fix-missing-ioctl-SIOCGSTAMP-add-sockios-header-linux-5.2.patch
Patch1: CVE-2026-4891.patch

BuildRequires: kernel-headers

Expand Down Expand Up @@ -66,6 +67,9 @@ EOF
%config /usr/share/dnsmasq/trust-anchors.conf

%changelog
* Fri May 15 2026 Azure Linux Security Servicing Account <azurelinux-security@microsoft.com> - 2.90-2
- Patch for CVE-2026-4891

* Thu Feb 22 2024 CBL-Mariner Servicing Account <cblmargh@microsoft.com> - 2.90-1
- Auto-upgrade to 2.90 - Azure Linux 3.0 Upgrades

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