2 files changed, 9 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index 4311db1d..a589fb33 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-12-18  Paul Eggert  <eggert@Penguin.CS.UCLA.EDU>
+
+	Fix memcpy issue found by -fsanitize=undefined
+	* field.c (set_record): Don't memcpy (databuf, NULL, 0),
+	as the C standard says the resulting behavior is undefined.
+
 2019-12-16         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* awkgram.y, command.y: Upgrade to Bison 3.5.
diff --git a/field.c b/field.c
index 8c7fe18e..28891c85 100644
--- a/field.c
+++ b/field.c
@@ -288,7 +288,9 @@ set_record(const char *buf, int cnt, const awk_fieldwidth_info_t *fw)
 		memset(databuf, '\0', databuf_size);
 	}
 	/* copy the data */
-	memcpy(databuf, buf, cnt);
+	if (cnt != 0) {
+		memcpy(databuf, buf, cnt);
+	}
 
 	/*
 	 * Add terminating '\0' so that C library routines