From patchwork Wed Jul 1 12:50:14 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Benjamin Robin (Schneider Electric)" X-Patchwork-Id: 91503 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97955C43458 for ; Wed, 1 Jul 2026 12:50:31 +0000 (UTC) Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) by mx.groups.io with SMTP id smtpd.msgproc02-g2.44362.1782910226630659911 for ; Wed, 01 Jul 2026 05:50:28 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@bootlin.com header.s=dkim header.b=p+RmK2Le; spf=pass (domain: bootlin.com, ip: 185.246.84.56, mailfrom: benjamin.robin@bootlin.com) Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id B64D01A0DB2 for ; Wed, 1 Jul 2026 12:50:24 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 8A77460288; Wed, 1 Jul 2026 12:50:24 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id EF62B104C9619; Wed, 1 Jul 2026 14:50:20 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1782910223; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding; bh=sAc1yew7BFhg83zE0YuIZL7ZtRRGyzWdVTEEQ9m1XRg=; b=p+RmK2LeUgFVauusSK9FR+09yR8lilDlK5Nbm6QAYuzOMQK4BCPOhZeesCUD48xGNGQ8kn tk3mJI0S+H76iz2GKcw4bFRNU5Y8NYxmjIYD6ckWq8IGNro5skquEDIse7QXvVbSr75Ptx jcsp2TTd642QD3WlXbzHBu7/njQ+4uGxmi6RU04Rz4UFcNggRsbY29Pj7P2rrzZ0nxR3g9 nJ8fazM8+fGiwhkItXmiAn4/wCap0U7xOvY5e24kn4IOGTZZDcVvqwy9dVKuZguVd4fWJF 11+kIyld+2d+aQptmwHP9ZyMHmykUIhVfQ2dZ2BzOWAxDGjL6QdL5Dh1KER0ng== From: "Benjamin Robin (Schneider Electric)" Date: Wed, 01 Jul 2026 14:50:14 +0200 Subject: [PATCH] dnsmasq: fix CVE-2026-4890 MIME-Version: 1.0 Message-Id: <20260701-dnsmasq-cve-2026-4890-v1-1-9daafc81fde3@bootlin.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/3WNzQ6CMBAGX4X0bJP+ILS8iuHQ7m61JqBQICaEd 7eIiSePs/l2ZmWJxkiJNcXKRlpiio8+gzwVDG6uvxKPmJkpoSpRC8mxT51LA4eF+H7kpbGCh7P Xrq6QtEOWf58jhfj6eC/twWn2d4Jpl30XIw1zDk7H7Ndriv81pazkARR6rRHJYLPIXeddIg6Pr otTU3gBCqrSOOmCsVQ7g1iCIjClDNqDIBQA3rJ2294yYgPvAgEAAA== X-Change-ID: 20260701-dnsmasq-cve-2026-4890-f5b3a76de3ad To: openembedded-devel@lists.openembedded.org Cc: olivier.benjamin@bootlin.com, mathieu.dubois-briand@bootlin.com, pascal.eberhard@se.com, wahid.essid@se.com, "Benjamin Robin (Schneider Electric)" X-Mailer: b4 0.15.2 X-Last-TLS-Session-Version: TLSv1.3 List-Id: X-Webhook-Received: from 45-33-107-173.ip.linodeusercontent.com [45.33.107.173] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Wed, 01 Jul 2026 12:50:31 -0000 X-Groupsio-URL: https://lists.openembedded.org/g/openembedded-devel/message/127994 A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet. This patch is used by debian bookworm (2.90-4_deb12u2). Signed-off-by: Benjamin Robin (Schneider Electric) --- This patch needs to be applied on top of the previous CVE-2026-2291 patch --- .../recipes-support/dnsmasq/dnsmasq_2.90.bb | 1 + .../dnsmasq/files/CVE-2026-4890.patch | 74 ++++++++++++++++++++++ 2 files changed, 75 insertions(+) --- base-commit: b0c2c648a1af89e7a8dd4c2ec841f3bc0ed0ccb9 change-id: 20260701-dnsmasq-cve-2026-4890-f5b3a76de3ad prerequisite-change-id: 20260701-dnsmasq-cve-2026-2291-fc2db33dde8d:v1 prerequisite-patch-id: e7e3fdcabd23649336d34bd2f492f09007d73472 Best regards, -- Benjamin Robin (Schneider Electric) diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb index 3a7af56c34d7..ad79a3bfa828 100644 --- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb +++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb @@ -21,6 +21,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV file://CVE-2026-4893.patch \ file://CVE-2026-5172.patch \ file://CVE-2026-2291.patch \ + file://CVE-2026-4890.patch \ " SRC_URI[sha256sum] = "8f6666b542403b5ee7ccce66ea73a4a51cf19dd49392aaccd37231a2c51b303b" diff --git a/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4890.patch b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4890.patch new file mode 100644 index 000000000000..1c60ae0b798f --- /dev/null +++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4890.patch @@ -0,0 +1,74 @@ +From 12e5ee3495842ededf8057758ef8da59745bbf33 Mon Sep 17 00:00:00 2001 +From: Simon Kelley +Date: Fri, 10 Apr 2026 22:16:45 +0100 +Subject: [PATCH] Fix NSEC bitmap parsing infinite loop. CVE-2026-4890 + +Report from Royce M . + +Location: dnssec.c:1290-1306, dnssec.c:1450-1463 + +The bitmap window iteration advances by p[1] instead of p[1]+2 (missing the 2-byte window header). With bitmap_length=0, both rdlen and p are +unchanged, causing an infinite loop and dnsmasq stops responding to all queries. + +The same code accesses p[2] after only checking rdlen >= 2 without verifying p[1] >= 1, causing OOB reads at 6 locations. + +Both bugs are reachable before RRSIG validation (confirmed by the source comment at line 2125), so no valid DNSSEC signatures are needed. + +CVE: CVE-2026-4890 +Upstream-Status: Backport [https://sources.debian.org/src/dnsmasq/2.90-4~deb12u2/debian/patches/CVE-2026-4890.patch] + +Signed-off-by: Benjamin Robin +--- + src/dnssec.c | 14 +++++++------- + 1 file changed, 7 insertions(+), 7 deletions(-) + +diff --git a/src/dnssec.c b/src/dnssec.c +index ed2f53ff..68f1b5d0 100644 +--- a/src/dnssec.c ++++ b/src/dnssec.c +@@ -1270,10 +1270,10 @@ static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsi + packet checked to be as long as rdlen implies in prove_non_existence() */ + + /* If we can prove that there's no NS record, return that information. */ +- if (nons && rdlen >= 2 && p[0] == 0 && (p[2] & (0x80 >> T_NS)) != 0) ++ if (nons && rdlen >= 2 && p[0] == 0 && p[1] >= 1 && (p[2] & (0x80 >> T_NS)) != 0) + *nons = 0; + +- if (rdlen >= 2 && p[0] == 0) ++ if (rdlen >= 2 && p[0] == 0 && p[1] >= 1) + { + /* A CNAME answer would also be valid, so if there's a CNAME is should + have been returned. */ +@@ -1301,8 +1301,8 @@ static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsi + break; /* finished checking */ + } + +- rdlen -= p[1]; +- p += p[1]; ++ rdlen -= p[1] + 2; ++ p += p[1] + 2; + } + + return 0; +@@ -1429,7 +1429,7 @@ static int check_nsec3_coverage(struct dns_header *header, size_t plen, int dige + p += hash_len; /* skip next-domain hash */ + rdlen -= p - psave; + +- if (rdlen >= 2 && p[0] == 0) ++ if (rdlen >= 2 && p[0] == 0 && p[1] >= 1) + { + /* If we can prove that there's no NS record, return that information. */ + if (nons && (p[2] & (0x80 >> T_NS)) != 0) +@@ -1458,8 +1458,8 @@ static int check_nsec3_coverage(struct dns_header *header, size_t plen, int dige + break; /* finished checking */ + } + +- rdlen -= p[1]; +- p += p[1]; ++ rdlen -= p[1] + 2; ++ p += p[1] + 2; + } + + return 1; +-- +2.43.0