From f5ef0f064c3f06b250a9eeda36dc239227658b00 Mon Sep 17 00:00:00 2001

From: Simon Kelley <simon@thekelleys.org.uk>

Date: Mon, 6 Mar 2023 23:00:58 +0000

Subject: [PATCH] Fix possible SEGV when no servers defined.

If there exists a --address=/<domain>/  or --server=/<domain>/#

configuration but no upstream server config unqualified by

domain then when a query which doesnt match the domain is

recieved it will use the qualfied server config and in the process

possibly make an out-of-bounds memory access.

Thanks to Daniel Danzberger for spotting the bug.

---

 CHANGELOG          | 11 +++++++++++

 src/domain-match.c |  5 +++--

 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/domain-match.c b/src/domain-match.c

index fe8e25a..9cc51e6 100644

--- a/src/domain-match.c

+++ b/src/domain-match.c

@@ -253,9 +253,10 @@ int lookup_domain(char *domain, int flags, int *lowout, int *highout)

   if (highout)

     *highout = nhigh;

-  if (nlow == nhigh)

+  /* qlen == -1 when we failed to match even an empty query, if there are no default servers. */

+  if (nlow == nhigh || qlen == -1)

     return 0;

-

+  

   return 1;

 }

-- 

2.33.7