Properly check certificate in case of export ciphers.

[openssl.git] / ssl / s2_pkt.c

diff --git a/ssl/s2_pkt.c b/ssl/s2_pkt.c
index 341b139b1622a82007ec4be466d48f4098330cc2..7a6188813431f345b2839a1b33873d99a272e3b1 100644 (file)
--- a/ssl/s2_pkt.c
+++ b/ssl/s2_pkt.c
@@ -535,19 +535,19 @@ static int n_do_ssl_write(SSL *s, const unsigned char *buf, unsigned int len)
             s->s2->three_byte_header = 0;
             p = 0;
         } else if ((bs <= 1) && (!s->s2->escape)) {
-                        /*-
-                         * j <= SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER, thus
-                         * j < SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER
-                         */
+            /*-
+             * j <= SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER, thus
+             * j < SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER
+             */
             s->s2->three_byte_header = 0;
             p = 0;
         } else {                /* we may have to use a 3 byte header */
 
-                        /*-
-                         * If s->s2->escape is not set, then
-                         * j <= SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER, and thus
-                         * j < SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER.
-                         */
+            /*-
+             * If s->s2->escape is not set, then
+             * j <= SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER, and thus
+             * j < SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER.
+             */
             p = (j % bs);
             p = (p == 0) ? 0 : (bs - p);
             if (s->s2->escape) {
@@ -559,12 +559,12 @@ static int n_do_ssl_write(SSL *s, const unsigned char *buf, unsigned int len)
         }
     }
 
-        /*-
-         * Now
-         *      j <= SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER
-         * holds, and if s->s2->three_byte_header is set, then even
-         *      j <= SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER.
-         */
+    /*-
+     * Now
+     *      j <= SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER
+     * holds, and if s->s2->three_byte_header is set, then even
+     *      j <= SSL2_MAX_RECORD_LENGTH_3_BYTE_HEADER.
+     */
 
     /*
      * mac_size is the number of MAC bytes len is the number of data bytes we
@@ -576,6 +576,20 @@ static int n_do_ssl_write(SSL *s, const unsigned char *buf, unsigned int len)
     s->s2->padding = p;
     s->s2->mac_data = &(s->s2->wbuf[3]);
     s->s2->wact_data = &(s->s2->wbuf[3 + mac_size]);
+
+    /*
+     * It would be clearer to write this as follows:
+     *     if (mac_size + len + p > SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER)
+     * However |len| is user input that could in theory be very large. We
+     * know |mac_size| and |p| are small, so to avoid any possibility of
+     * overflow we write it like this.
+     *
+     * In theory this should never fail because the logic above should have
+     * modified |len| if it is too big. But we are being cautious.
+     */
+    if (len > (SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER - (mac_size + p))) {
+        return -1;
+    }
     /* we copy the data into s->s2->wbuf */
     memcpy(s->s2->wact_data, buf, len);
     if (p)