Fix a null-pointer dereference in establish_http_proxy_passthru()

Prevents that the client crashes if the peer does not specify
the 'realm' and/or 'nonce' values. These pointers are
dereferenced in DigestCalcHA1() and DigestCalcResponse();
hence, if not set, a null-pointer dereference would occur.

Signed-off-by: Guido Vranken <guidovranken@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1497574736-2092-1-git-send-email-gv@guidovranken.nl>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14844.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/proxy.c b/src/openvpn/proxy.c
index 05f362dc2d344fc35e0dec09718464e11ba4f011..46cb2bb031d8b89d635fc0e05a1abaca92063bab 100644 (file)
--- a/src/openvpn/proxy.c
+++ b/src/openvpn/proxy.c
@@ -875,6 +875,13 @@ establish_http_proxy_passthru(struct http_proxy_info *p,
                 const char *algor = get_pa_var("algorithm", pa, &gc);
                 const char *opaque = get_pa_var("opaque", pa, &gc);
 
+                if ( !realm || !nonce )
+                {
+                    msg(D_LINK_ERRORS, "HTTP proxy: digest auth failed, malformed response "
+                            "from server: realm= or nonce= missing" );
+                    goto error;
+                }
+
                 /* generate a client nonce */
                 ASSERT(rand_bytes(cnonce_raw, sizeof(cnonce_raw)));
                 cnonce = make_base64_string2(cnonce_raw, sizeof(cnonce_raw), &gc);