From 544d576b0076dcb96b78e502e2c05906486ba357 Mon Sep 17 00:00:00 2001
From: Jakub Jelen <jjelen@redhat.com>
Date: Thu, 17 Oct 2019 14:59:54 +0200
Subject: [PATCH] asn1: Do not pass null argument to memcpy

Reported by clang analyzer:

src/libopensc/asn1.c:1080:2: note: Null pointer passed as an argument to a 'nonnull' parameter

        memcpy(p, data, datalen);
---
 src/libopensc/asn1.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libopensc/asn1.c b/src/libopensc/asn1.c
index df074e40..8caac84b 100644
--- a/src/libopensc/asn1.c
+++ b/src/libopensc/asn1.c
@@ -1029,7 +1029,9 @@ static int asn1_write_element(sc_context_t *ctx, unsigned int tag,
 	else   {
 		*p++ = datalen & 0x7F;
 	}
-	memcpy(p, data, datalen);
+	if (datalen && data) {
+		memcpy(p, data, datalen);
+	}
 
 	return SC_SUCCESS;
 }