2 files changed, 11 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index a5cb06484..e05b8698c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,10 @@
      [readconf.c]
      when processing Match blocks, skip 'exec' clauses if previous predicates
      failed to match; ok markus@
+   - djm@cvs.openbsd.org 2014/02/23 20:03:42
+     [ssh-ed25519.c]
+     check for unsigned overflow; not reachable in OpenSSH but others might
+     copy our code...
 
 20140213
  - (dtucker) [configure.ac openbsd-compat/openssl-compat.{c,h}]  Add compat
diff --git a/ssh-ed25519.c b/ssh-ed25519.c
index 56c480df2..160d1f23b 100644
--- a/ssh-ed25519.c
+++ b/ssh-ed25519.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-ed25519.c,v 1.2 2014/02/02 03:44:31 djm Exp $ */
+/* $OpenBSD: ssh-ed25519.c,v 1.3 2014/02/23 20:03:42 djm Exp $ */
 /*
  * Copyright (c) 2013 Markus Friedl <markus@openbsd.org>
  *
@@ -21,6 +21,7 @@
 
 #include "crypto_api.h"
 
+#include <limits.h>
 #include <string.h>
 #include <stdarg.h>
 
@@ -45,6 +46,11 @@ ssh_ed25519_sign(const Key *key, u_char **sigp, u_int *lenp,
                 error("%s: no ED25519 key", __func__);
                 return -1;
         }
+
+        if (datalen >= UINT_MAX - crypto_sign_ed25519_BYTES) {
+                error("%s: datalen %u too long", __func__, datalen);
+                return -1;
+        }
         smlen = slen = datalen + crypto_sign_ed25519_BYTES;
         sig = xmalloc(slen);