tor

commit 8505522e508c8d2379afbd86154a910948cf8c70
parent ef234ba303a358f956d4c2afded388b54cfc91bc
Author: Nick Mathewson <nickm@torproject.org>
Date:   Mon, 16 Jul 2018 07:51:11 -0400

Avoid a use-after-null-check in proto_socks.c

Coverity rightly complains that early in the function we're checking
whether username is NULL, and later we're passing it unconditionally
to strlen().

Fixes CID 1437967.  Bug not in any released Tor.

Diffstat:
M
src/core/proto/proto_socks.c
 | 
4
++--

1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/core/proto/proto_socks.c b/src/core/proto/proto_socks.c
@@ -166,7 +166,7 @@ parse_socks4_request(const uint8_t *raw_data, socks_request_t *req,
   *is_socks4a = (dest_ip >> 8) == 0;
 
   const char *username = socks4_client_request_get_username(trunnel_req);
-  size_t usernamelen = username ? strlen(username) : 0;
+  const size_t usernamelen = username ? strlen(username) : 0;
   if (username && usernamelen) {
     if (usernamelen > MAX_SOCKS_MESSAGE_LEN) {
       log_warn(LD_APP, "Socks4 user name too long; rejecting.");
@@ -184,7 +184,7 @@ parse_socks4_request(const uint8_t *raw_data, socks_request_t *req,
     // We cannot rely on trunnel here, as we want to detect if
     // we have abnormally long hostname field.
     const char *hostname = (char *)raw_data + SOCKS4_NETWORK_LEN +
-     strlen(username) + 1;
+     usernamelen + 1;
     size_t hostname_len = (char *)raw_data + datalen - hostname;
 
     if (hostname_len <= sizeof(req->address)) {