gpg: Fix a NULL-deref due to empty ring trust packets.

* g10/parse-packet.c (parse_trust): Always allocate a packet.
--

Reported-by: Hanno Böck <[email protected]>
Signed-off-by: Werner Koch <[email protected]>

(back ported from commit 39978487863066e59bb657f5fe4e8baab510da7e)

1 files changed, 5 insertions, 3 deletions

diff --git a/g10/parse-packet.c b/g10/parse-packet.c
index c374477e4..7b379c131 100644
--- a/g10/parse-packet.c
+++ b/g10/parse-packet.c
@@ -2324,11 +2324,11 @@ parse_trust( IOBUF inp, int pkttype, unsigned long pktlen, PACKET *pkt )
 
   (void)pkttype;
 
+  pkt->pkt.ring_trust = xmalloc( sizeof *pkt->pkt.ring_trust );
   if (pktlen)
     {
       c = iobuf_get_noeof(inp);
       pktlen--;
-      pkt->pkt.ring_trust = xmalloc( sizeof *pkt->pkt.ring_trust );
       pkt->pkt.ring_trust->trustval = c;
       pkt->pkt.ring_trust->sigcache = 0;
       if (!c && pktlen==1)
@@ -2346,8 +2346,10 @@ parse_trust( IOBUF inp, int pkttype, unsigned long pktlen, PACKET *pkt )
     }
   else
     {
-      if( list_mode )
-	fprintf (listfp, ":trust packet: empty\n");
+      pkt->pkt.ring_trust->trustval = 0;
+      pkt->pkt.ring_trust->sigcache = 0;
+      if (list_mode)
+        fprintf (listfp, ":trust packet: empty\n");
     }
   iobuf_skip_rest (inp, pktlen, 0);
 }