Fix segfault if the server maliciously sends the wrong type of key

[u/mdw/putty] / ssh.c

diff --git a/ssh.c b/ssh.c
index e2c2d73..a41e3bf 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -2955,8 +2955,9 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
 #endif
 
     hkey = hostkey->newkey(hostkeydata, hostkeylen);
-    if (!hostkey->verifysig(hkey, sigdata, siglen, exchange_hash, 20)) {
-       bombout(("Server failed host key check"));
+    if (!hkey ||
+       !hostkey->verifysig(hkey, sigdata, siglen, exchange_hash, 20)) {
+       bombout(("Server's host key did not match the signature supplied"));
        crReturn(0);
     }