From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Tue, 19 Feb 2019 19:27:50 +0000 (+0100)
Subject: lib/utils kr_memreserve(): fix a ubsan nitpick
X-Git-Tag: v4.0.0~28^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=95da3e0700ab251d3abf87fb8f862d7e18a429e0;p=thirdparty%2Fknot-resolver.git

lib/utils kr_memreserve(): fix a ubsan nitpick
---

diff --git a/lib/utils.c b/lib/utils.c
index 09194bf0e..46b97f673 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -229,8 +229,10 @@ int kr_memreserve(void *baton, char **mem, size_t elm_size, size_t want, size_t
         size_t next_size = array_next_count(want);
         void *mem_new = mm_alloc(pool, next_size * elm_size);
         if (mem_new != NULL) {
-            memcpy(mem_new, *mem, (*have)*(elm_size));
-            mm_free(pool, *mem);
+	    if (*mem) { /* 0-length memcpy from NULL isn't technically OK */
+		memcpy(mem_new, *mem, (*have)*(elm_size));
+		mm_free(pool, *mem);
+	    }
             *mem = mem_new;
             *have = next_size;
             return 0;