Hi, On Wed, Jul 1, 2026 at 8:55 PM Benjamin Robin via lists.openembedded.org <[email protected]> wrote: > > 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) > <[email protected]> > --- > This patch needs to be applied on top of the previous CVE-2026-2291 patch > --- > Changes in v2: > - Fix email subject > - Link to v1: > https://patch.msgid.link/[email protected] > --- > .../recipes-support/dnsmasq/dnsmasq_2.90.bb | 1 + > .../dnsmasq/files/CVE-2026-4890.patch | 74 > ++++++++++++++++++++++
This doesn't apply. patching file src/dnssec.c Hunk #1 FAILED at 1270. Hunk #2 FAILED at 1301. Hunk #3 succeeded at 1433 (offset 4 lines). Hunk #4 FAILED at 1458. 3 out of 4 hunks FAILED -- rejects in file src/dnssec.c Patch CVE-2026-4890.patch does not apply (enforce with -f) The final patch merged upstream for this seems different from this earlier version. But, it'd be good to mention source as: https://thekelleys.org.uk/dnsmasq/CVE/CVE-2026-4890.dnsmasq-2.91.diff > 2 files changed, 75 insertions(+) > > 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 <[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://sources.debian.org/src/dnsmasq/2.90-4~deb12u2/debian/patches/CVE-2026-4890.patch] > + > +Signed-off-by: Benjamin Robin <[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 > > --- > 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) <[email protected]> > > > >
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