From: "Hugo SIMELIERE (Schneider Electric)" <[email protected]>
Pick patch from [1] dnsmasq 2.90 debian bookworm pacthes. [1] https://sources.debian.org/src/dnsmasq/2.90-4~deb12u2/debian/patches/CVE-2026-4890.patch Signed-off-by: Hugo SIMELIERE (Schneider Electric) <[email protected]> Reviewed-by: Bruno VERNAY <[email protected]> --- .../recipes-support/dnsmasq/dnsmasq_2.90.bb | 1 + .../dnsmasq/files/CVE-2026-4890.patch | 75 +++++++++++++++++++ 2 files changed, 76 insertions(+) create mode 100644 meta-networking/recipes-support/dnsmasq/files/CVE-2026-4890.patch diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb index 3281404e42..ecd17fa426 100644 --- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb +++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb @@ -17,6 +17,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV file://dnsmasq-noresolvconf.service \ file://dnsmasq-resolved.conf \ 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 0000000000..0b25239a86 --- /dev/null +++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4890.patch @@ -0,0 +1,75 @@ +From 12e5ee3495842ededf8057758ef8da59745bbf33 Mon Sep 17 00:00:00 2001 +From: Simon Kelley <[email protected]> +Date: Fri, 10 Apr 2026 22:16:45 +0100 +Subject: [PATCH] Fix NSEC bitmap parsing infinite loop. CVE-2026-4890 + +Report from Royce M <[email protected]>. + +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://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=7b151eb60609a0139474918222806f9bcfb4fe71] + +Signed-off-by: Hugo SIMELIERE (Schneider Electric) <[email protected]> +--- + 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 + -- 2.43.0
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