From 4d3ef152a5d0a3cf053d41ea950823bfcc0ea5c2 Mon Sep 17 00:00:00 2001 From: xiaoweiwei Date: Tue, 28 Jul 2020 10:32:50 +0800 Subject: [PATCH] underflow --- src/rfc1035.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/rfc1035.c b/src/rfc1035.c index fefe63d..d3cce6f 100644 --- a/src/rfc1035.c +++ b/src/rfc1035.c @@ -1340,6 +1340,9 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen, size_t len; int rd_bit = (header->hb3 & HB3_RD); + // Make sure we do not underflow here too + if (qlen > (limit - ((char *)header))) return 0; + /* never answer queries with RD unset, to avoid cache snooping. */ if (ntohs(header->ancount) != 0 || ntohs(header->nscount) != 0 || -- 1.8.3.1