The branch OpenSSL_1_0_1-stable has been updated
       via  bb1a4866034255749ac578adb06a76335fc117b1 (commit)
       via  8289755d54e4cf34d502c630613d1dba60e30830 (commit)
       via  aa388af1e18988894a48b8f64ae994eaa4366d5d (commit)
      from  52e623c4cb06fffa9d5e75c60b34b4bc130b12e9 (commit)


- Log -----------------------------------------------------------------
commit bb1a4866034255749ac578adb06a76335fc117b1
Author: Dr. Stephen Henson <st...@openssl.org>
Date:   Wed Sep 21 13:26:01 2016 +0100

    Make message buffer slightly larger than message.
    
    Grow TLS/DTLS 16 bytes more than strictly necessary as a precaution against
    OOB reads. In most cases this will have no effect because the message buffer
    will be large enough already.
    
    Reviewed-by: Matt Caswell <m...@openssl.org>
    (cherry picked from commit 006a788c84e541c8920dd2ad85fb62b52185c519)

commit 8289755d54e4cf34d502c630613d1dba60e30830
Author: Dr. Stephen Henson <st...@openssl.org>
Date:   Wed Sep 21 12:54:13 2016 +0100

    Use SSL3_HM_HEADER_LENGTH instead of 4.
    
    Reviewed-by: Matt Caswell <m...@openssl.org>
    (cherry picked from commit bc9563f83d28342b5ec0073ec12d9e581e4f3317)

commit aa388af1e18988894a48b8f64ae994eaa4366d5d
Author: Dr. Stephen Henson <st...@openssl.org>
Date:   Wed Sep 21 12:57:01 2016 +0100

    Remove unnecessary check.
    
    The overflow check will never be triggered because the
    the n2l3 result is always less than 2^24.
    
    Reviewed-by: Matt Caswell <m...@openssl.org>
    (cherry picked from commit 709ec8b3848e2ac201b86f49c5561debb8572ccd)

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

Summary of changes:
 ssl/d1_both.c |  5 ++++-
 ssl/s3_both.c | 35 ++++++++++++++++++++---------------
 2 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/ssl/d1_both.c b/ssl/d1_both.c
index ae292c4..0cf1e49 100644
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.c
@@ -577,9 +577,12 @@ static int dtls1_preprocess_fragment(SSL *s, struct 
hm_header_st *msg_hdr,
         /*
          * msg_len is limited to 2^24, but is effectively checked against max
          * above
+         *
+         * Make buffer slightly larger than message length as a precaution
+         * against small OOB reads e.g. CVE-2016-6306
          */
         if (!BUF_MEM_grow_clean
-            (s->init_buf, msg_len + DTLS1_HM_HEADER_LENGTH)) {
+            (s->init_buf, msg_len + DTLS1_HM_HEADER_LENGTH + 16)) {
             SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT, ERR_R_BUF_LIB);
             return SSL_AD_INTERNAL_ERROR;
         }
diff --git a/ssl/s3_both.c b/ssl/s3_both.c
index c51fc6e..d798d83 100644
--- a/ssl/s3_both.c
+++ b/ssl/s3_both.c
@@ -427,21 +427,22 @@ long ssl3_get_message(SSL *s, int st1, int stn, int mt, 
long max, int *ok)
         }
         *ok = 1;
         s->state = stn;
-        s->init_msg = s->init_buf->data + 4;
+        s->init_msg = s->init_buf->data + SSL3_HM_HEADER_LENGTH;
         s->init_num = (int)s->s3->tmp.message_size;
         return s->init_num;
     }
 
     p = (unsigned char *)s->init_buf->data;
 
-    if (s->state == st1) {      /* s->init_num < 4 */
+    if (s->state == st1) {      /* s->init_num < SSL3_HM_HEADER_LENGTH */
         int skip_message;
 
         do {
-            while (s->init_num < 4) {
+            while (s->init_num < SSL3_HM_HEADER_LENGTH) {
                 i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE,
                                               &p[s->init_num],
-                                              4 - s->init_num, 0);
+                                              SSL3_HM_HEADER_LENGTH -
+                                              s->init_num, 0);
                 if (i <= 0) {
                     s->rwstate = SSL_READING;
                     *ok = 0;
@@ -465,12 +466,13 @@ long ssl3_get_message(SSL *s, int st1, int stn, int mt, 
long max, int *ok)
 
                         if (s->msg_callback)
                             s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
-                                            p, 4, s, s->msg_callback_arg);
+                                            p, SSL3_HM_HEADER_LENGTH, s,
+                                            s->msg_callback_arg);
                     }
         }
         while (skip_message);
 
-        /* s->init_num == 4 */
+        /* s->init_num == SSL3_HM_HEADER_LENGTH */
 
         if ((mt >= 0) && (*p != mt)) {
             al = SSL_AD_UNEXPECTED_MESSAGE;
@@ -497,19 +499,20 @@ long ssl3_get_message(SSL *s, int st1, int stn, int mt, 
long max, int *ok)
             SSLerr(SSL_F_SSL3_GET_MESSAGE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
             goto f_err;
         }
-        if (l > (INT_MAX - 4)) { /* BUF_MEM_grow takes an 'int' parameter */
-            al = SSL_AD_ILLEGAL_PARAMETER;
-            SSLerr(SSL_F_SSL3_GET_MESSAGE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
-            goto f_err;
-        }
-        if (l && !BUF_MEM_grow_clean(s->init_buf, (int)l + 4)) {
+        /*
+         * Make buffer slightly larger than message length as a precaution
+         * against small OOB reads e.g. CVE-2016-6306
+         */
+        if (l
+            && !BUF_MEM_grow_clean(s->init_buf,
+                                   (int)l + SSL3_HM_HEADER_LENGTH + 16)) {
             SSLerr(SSL_F_SSL3_GET_MESSAGE, ERR_R_BUF_LIB);
             goto err;
         }
         s->s3->tmp.message_size = l;
         s->state = stn;
 
-        s->init_msg = s->init_buf->data + 4;
+        s->init_msg = s->init_buf->data + SSL3_HM_HEADER_LENGTH;
         s->init_num = 0;
     }
 
@@ -538,10 +541,12 @@ long ssl3_get_message(SSL *s, int st1, int stn, int mt, 
long max, int *ok)
 #endif
 
     /* Feed this message into MAC computation. */
-    ssl3_finish_mac(s, (unsigned char *)s->init_buf->data, s->init_num + 4);
+    ssl3_finish_mac(s, (unsigned char *)s->init_buf->data,
+                    s->init_num + SSL3_HM_HEADER_LENGTH);
     if (s->msg_callback)
         s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, s->init_buf->data,
-                        (size_t)s->init_num + 4, s, s->msg_callback_arg);
+                        (size_t)s->init_num + SSL3_HM_HEADER_LENGTH, s,
+                        s->msg_callback_arg);
     *ok = 1;
     return s->init_num;
  f_err:
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