[openssl-commits] [openssl] OpenSSL_1_0_0-stable update

[Matt Caswell]

The branch OpenSSL_1_0_0-stable has been updated
       via  923552bd5de08997523bd6d25323217fab5e83be (commit)
      from  dafa9534de489bbb0c496eae628cacadcdd01821 (commit)


- Log -----------------------------------------------------------------
commit 923552bd5de08997523bd6d25323217fab5e83be
Author: Matt Caswell <matt at openssl.org>
Date:   Fri Apr 10 17:25:27 2015 +0100

    Check for ClientHello message overruns
    
    The ClientHello processing is insufficiently rigorous in its checks to make
    sure that we don't read past the end of the message. This does not have
    security implications due to the size of the underlying buffer - but still
    needs to be fixed.
    
    With thanks to Qinghao Tang for reporting this issue.
    
    Reviewed-by: Rich Salz <rsalz at openssl.org>
    (cherry picked from commit c9642eb1ff79a30e2c7632ef8267cc34cc2b0d79)

-----------------------------------------------------------------------

Summary of changes:
 ssl/s3_srvr.c | 42 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index dc582ea..8e30083 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -843,6 +843,16 @@ int ssl3_get_client_hello(SSL *s)
     d = p = (unsigned char *)s->init_msg;
 
     /*
+     * 2 bytes for client version, SSL3_RANDOM_SIZE bytes for random, 1 byte
+     * for session id length
+     */
+    if (n < 2 + SSL3_RANDOM_SIZE + 1) {
+        al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+        goto f_err;
+    }
+
+    /*
      * use version from inside client hello, not from record header (may
      * differ: see RFC 2246, Appendix E, second paragraph)
      */
@@ -872,6 +882,12 @@ int ssl3_get_client_hello(SSL *s)
         unsigned int session_length, cookie_length;
 
         session_length = *(p + SSL3_RANDOM_SIZE);
+
+        if (p + SSL3_RANDOM_SIZE + session_length + 1 >= d + n) {
+            al = SSL_AD_DECODE_ERROR;
+            SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+            goto f_err;
+        }
         cookie_length = *(p + SSL3_RANDOM_SIZE + session_length + 1);
 
         if (cookie_length == 0)
@@ -885,6 +901,12 @@ int ssl3_get_client_hello(SSL *s)
     /* get the session-id */
     j = *(p++);
 
+    if (p + j > d + n) {
+        al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+        goto f_err;
+    }
+
     s->hit = 0;
     /*
      * Versions before 0.9.7 always allow session reuse during renegotiation
@@ -916,8 +938,19 @@ int ssl3_get_client_hello(SSL *s)
 
     if (s->version == DTLS1_VERSION || s->version == DTLS1_BAD_VER) {
         /* cookie stuff */
+        if (p + 1 > d + n) {
+            al = SSL_AD_DECODE_ERROR;
+            SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+            goto f_err;
+        }
         cookie_len = *(p++);
 
+        if (p + cookie_len > d + n) {
+            al = SSL_AD_DECODE_ERROR;
+            SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+            goto f_err;
+        }
+
         /*
          * The ClientHello may contain a cookie even if the
          * HelloVerify message has not been sent--make sure that it
@@ -958,6 +991,11 @@ int ssl3_get_client_hello(SSL *s)
         p += cookie_len;
     }
 
+    if (p + 2 > d + n) {
+        al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
+        goto f_err;
+    }
     n2s(p, i);
     if ((i == 0) && (j != 0)) {
         /* we need a cipher if we are not resuming a session */
@@ -965,7 +1003,9 @@ int ssl3_get_client_hello(SSL *s)
         SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_NO_CIPHERS_SPECIFIED);
         goto f_err;
     }
-    if ((p + i) >= (d + n)) {
+
+    /* i bytes of cipher data + 1 byte for compression length later */
+    if ((p + i + 1) > (d + n)) {
         /* not enough data */
         al = SSL_AD_DECODE_ERROR;
         SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);