From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Tue, 6 Apr 2021 17:55:58 +0000 (+0200)
Subject: treewide: fix instances of memcpy(*, NULL, 0)
X-Git-Tag: v3.1.0~175^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bd5f890124fe958fb87272fbc2b2ca0e5930ddde;p=thirdparty%2Fknot-dns.git

treewide: fix instances of memcpy(*, NULL, 0)

I don't think they could cause any practical issues,
but they popped out when using sanitizing Knot with Resolver.
---

diff --git a/src/contrib/vpool/vpool.c b/src/contrib/vpool/vpool.c
index b7c03057b8..f130a47ded 100644
--- a/src/contrib/vpool/vpool.c
+++ b/src/contrib/vpool/vpool.c
@@ -88,7 +88,9 @@ vpool_resize(struct vpool *pool, size_t datsize)
 			return (ENOMEM);
 		}
 
-		memcpy(ret, pool->v_buf, pool->v_off);
+		if (pool->v_off > 0) {
+			memcpy(ret, pool->v_buf, pool->v_off);
+		}
 		free(pool->v_basebuf);
 		pool->v_basebuf = pool->v_buf = ret;
 		pool->v_size = size;
diff --git a/src/libknot/packet/pkt.c b/src/libknot/packet/pkt.c
index ddda72e497..381a8dee6e 100644
--- a/src/libknot/packet/pkt.c
+++ b/src/libknot/packet/pkt.c
@@ -157,13 +157,13 @@ static int pkt_rr_array_alloc(knot_pkt_t *pkt, uint16_t count)
 		return KNOT_ENOMEM;
 	}
 
-	/* Copy the old data. */
-	memcpy(rr_info, pkt->rr_info, pkt->rrset_allocd * sizeof(knot_rrinfo_t));
-	memcpy(rr, pkt->rr, pkt->rrset_allocd * sizeof(knot_rrset_t));
-
-	/* Reassign and free old data. */
-	mm_free(&pkt->mm, pkt->rr);
-	mm_free(&pkt->mm, pkt->rr_info);
+	/* Copy and free the old data, if any. */
+	if (pkt->rrset_allocd > 0) {
+		memcpy(rr_info, pkt->rr_info, pkt->rrset_allocd * sizeof(knot_rrinfo_t));
+		memcpy(rr, pkt->rr, pkt->rrset_allocd * sizeof(knot_rrset_t));
+		mm_free(&pkt->mm, pkt->rr);
+		mm_free(&pkt->mm, pkt->rr_info);
+	}
 	pkt->rr = rr;
 	pkt->rr_info = rr_info;
 	pkt->rrset_allocd = next_size;