Commit 25833cef authored by Michael Catanzaro's avatar Michael Catanzaro Committed by Philip Withnall
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gsocks4aproxy: Fix a single byte buffer overflow in connect messages 

`SOCKS4_CONN_MSG_LEN` failed to account for the length of the final nul
byte in the connect message, which is an addition in SOCKSv4a vs
SOCKSv4.

This means that the buffer for building and transmitting the connect
message could be overflowed if the username and hostname are both
`SOCKS4_MAX_LEN` (255) bytes long.

Proxy configurations are normally statically configured, so the username
is very unlikely to be near its maximum length, and hence this overflow
is unlikely to be triggered in practice.

(Commit message by Philip Withnall, diagnosis and fix by Michael
Catanzaro.)

Fixes: #3461
parent 1adc303f

gio/gsocks4aproxy.c

+2 −2
Changes for gio/gsocks4aproxy.c: 2 added lines, 2 removed lines.
Original line number Diff line number Diff line
@@ -79,9 +79,9 @@ g_socks4a_proxy_init (GSocks4aProxy *proxy) 
 * +----+----+----+----+----+----+----+----+----+----+....+----+------+....+------+

 * | VN | CD | DSTPORT |      DSTIP        | USERID       |NULL| HOST |    | NULL |

 * +----+----+----+----+----+----+----+----+----+----+....+----+------+....+------+

 *    1    1      2              4           variable       1    variable

 *    1    1      2              4           variable       1    variable    1

 */

#define SOCKS4_CONN_MSG_LEN	    (9 + SOCKS4_MAX_LEN * 2)

#define SOCKS4_CONN_MSG_LEN	    (10 + SOCKS4_MAX_LEN * 2)

static gint

set_connect_msg (guint8      *msg,

		 const gchar *hostname,