gpg: Do not read from uninitialized memory with --list-packets.

* g10/parse-packet.c (parse_plaintext): Fill up the allocated NAME.
--

This actually does not harm because we merely display a buffer
allocated by ourselves.  However, we better tell Valgrind about it so
that we don't need to track this thing down ever again.

Test using a corrupted literal data packet:

  echo cb 0a 75 ff 59 ae 90 d5  74 65 73 74 | \
    undump |\
    valgrind gpg --list-packets >/dev/null

Reported-by: Sebastian Schinzel
Signed-off-by: Werner Koch <wk@gnupg.org>

g10/parse-packet.c

@@ -3087,6 +3087,12 @@ parse_plaintext (IOBUF inp, int pkttype, unsigned long pktlen,
 	else
 	  pt->name[i] = c;
     }
+  /* Fill up NAME so that a check with valgrind won't complain about
+   * reading from uninitalized memory.  This case may be triggred by
+   * corrupted packets.  */
+  for (; i < namelen; i++)
+    pt->name[i] = 0;
+
   pt->timestamp = read_32 (inp);
   if (pktlen)
     pktlen -= 4;