From 1c85901cc4c0f7693183f4b280604619e56cba00 Mon Sep 17 00:00:00 2001
From: "W.C.A. Wijngaards" <wouter@nlnetlabs.nl>
Date: Wed, 16 Aug 2023 16:58:49 +0200
Subject: [PATCH] - Fix out of bounds read in parse_edns_options_from_query, it
 would read   8 bytes after a client option of length 8, and then ignore them
 to   recreate a 24 byte response. The fixup does not read out of bounds,  
 and puts zeroes in the buffer at that point, that then are ignored.

---
 util/data/msgparse.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/util/data/msgparse.c b/util/data/msgparse.c
index 40189d613..b5414c6d0 100644
--- a/util/data/msgparse.c
+++ b/util/data/msgparse.c
@@ -1049,7 +1049,12 @@ parse_edns_options_from_query(uint8_t* rdata_ptr, size_t rdata_len,
 			/* Copy client cookie, version and timestamp for
 			 * validation and creation purposes.
 			 */
-			memmove(server_cookie, rdata_ptr, 16);
+			if(opt_len >= 16) {
+				memmove(server_cookie, rdata_ptr, 16);
+			} else {
+				memset(server_cookie, 0, 16);
+				memmove(server_cookie, rdata_ptr, opt_len);
+			}
 
 			/* In the "if, if else" block below, we validate a
 			 * RFC9018 cookie. If it doesn't match the recipe, or
