From 21ad035cc9fef070df8ff09aaebad604411442c7 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Tue, 26 May 2009 09:29:02 +0000
Subject: Fix a signal cleanup problem. Fix zero length MPI reading.

---
 g10/parse-packet.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

(limited to 'g10/parse-packet.c')

diff --git a/g10/parse-packet.c b/g10/parse-packet.c
index fd01e7635..324ab5e2e 100644
--- a/g10/parse-packet.c
+++ b/g10/parse-packet.c
@@ -139,9 +139,19 @@ mpi_read (iobuf_t inp, unsigned int *ret_nread, int secure)
       p[i+2] = iobuf_get(inp) & 0xff;
       nread++;
     }
-  if ( gcry_mpi_scan( &a, GCRYMPI_FMT_PGP, buf, nread, &nread ) )
-    a = NULL;
-    
+
+  if (nread >= 2 && !(buf[0] << 8 | buf[1]))
+    {
+      /* Libgcrypt < 1.5.0 accidently rejects zero-length (i.e. zero)
+         MPIs.  We fix this here.  */
+      a = gcry_mpi_new (0);
+    }
+  else
+    {
+      if ( gcry_mpi_scan( &a, GCRYMPI_FMT_PGP, buf, nread, &nread ) )
+        a = NULL;
+    }
+
  leave:
   gcry_free(buf);
   if ( nread > *ret_nread )
-- 
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