From f158664062e049ec4604f6e772551a00575011f4 Mon Sep 17 00:00:00 2001 From: Simon Kelley Date: Mon, 30 Mar 2026 16:24:33 +0100 Subject: [PATCH] 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: Hugo SIMELIERE (Schneider Electric) --- src/rfc1035.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/rfc1035.c b/src/rfc1035.c index 387d894a..32dc5711 100644 --- a/src/rfc1035.c +++ b/src/rfc1035.c @@ -932,7 +932,8 @@ 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, 1, 0)) + /* rdlen may lie, and extract_name() advances p1 past where it says the record ends. */ + if (!extract_name(header, qlen, &p1, name, 1, 0) || (p1 > endrr)) { blockdata_free(addr.rrblock.rrdata); return 2; -- 2.43.0