Add heartbeat extension bounds check.
authorDr. Stephen Henson <steve@openssl.org>
Sat, 5 Apr 2014 23:51:06 +0000 (00:51 +0100)
committerDr. Stephen Henson <steve@openssl.org>
Mon, 7 Apr 2014 18:44:38 +0000 (19:44 +0100)
A missing bounds check in the handling of the TLS heartbeat extension
can be used to reveal up to 64k of memory to a connected client or
server.

Thanks for Neel Mehta of Google Security for discovering this bug and to
Adam Langley <agl@chromium.org> and Bodo Moeller <bmoeller@acm.org> for
preparing the fix (CVE-2014-0160)
(cherry picked from commit 96db9023b881d7cd9f379b0c154650d6c108e9a3)

CHANGES
ssl/d1_both.c
ssl/t1_lib.c

diff --git a/CHANGES b/CHANGES
index be2212d..87333bf 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,15 @@
 
  Changes between 1.0.2 and 1.1.0  [xx XXX xxxx]
 
+  *) A missing bounds check in the handling of the TLS heartbeat extension
+     can be used to reveal up to 64k of memory to a connected client or
+     server.
+
+     Thanks for Neel Mehta of Google Security for discovering this bug and to
+     Adam Langley <agl@chromium.org> and Bodo Moeller <bmoeller@acm.org> for
+     preparing the fix (CVE-2014-0160)
+     [Adam Langley, Bodo Moeller]
+
   *) Fix for the attack described in the paper "Recovering OpenSSL
      ECDSA Nonces Using the FLUSH+RELOAD Cache Side-channel Attack"
      by Yuval Yarom and Naomi Benger. Details can be obtained from:
index f0c5962..d8bcd58 100644 (file)
@@ -1330,26 +1330,36 @@ dtls1_process_heartbeat(SSL *s)
        unsigned int payload;
        unsigned int padding = 16; /* Use minimum padding */
 
-       /* Read type and payload length first */
-       hbtype = *p++;
-       n2s(p, payload);
-       pl = p;
-
        if (s->msg_callback)
                s->msg_callback(0, s->version, TLS1_RT_HEARTBEAT,
                        &s->s3->rrec.data[0], s->s3->rrec.length,
                        s, s->msg_callback_arg);
 
+       /* Read type and payload length first */
+       if (1 + 2 + 16 > s->s3->rrec.length)
+               return 0; /* silently discard */
+       hbtype = *p++;
+       n2s(p, payload);
+       if (1 + 2 + payload + 16 > s->s3->rrec.length)
+               return 0; /* silently discard per RFC 6520 sec. 4 */
+       pl = p;
+
        if (hbtype == TLS1_HB_REQUEST)
                {
                unsigned char *buffer, *bp;
+               unsigned int write_length = 1 /* heartbeat type */ +
+                                           2 /* heartbeat length */ +
+                                           payload + padding;
                int r;
 
+               if (write_length > SSL3_RT_MAX_PLAIN_LENGTH)
+                       return 0;
+
                /* Allocate memory for the response, size is 1 byte
                 * message type, plus 2 bytes payload length, plus
                 * payload, plus padding
                 */
-               buffer = OPENSSL_malloc(1 + 2 + payload + padding);
+               buffer = OPENSSL_malloc(write_length);
                bp = buffer;
 
                /* Enter response type, length and copy payload */
@@ -1360,11 +1370,11 @@ dtls1_process_heartbeat(SSL *s)
                /* Random padding */
                RAND_pseudo_bytes(bp, padding);
 
-               r = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buffer, 3 + payload + padding);
+               r = dtls1_write_bytes(s, TLS1_RT_HEARTBEAT, buffer, write_length);
 
                if (r >= 0 && s->msg_callback)
                        s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
-                               buffer, 3 + payload + padding,
+                               buffer, write_length,
                                s, s->msg_callback_arg);
 
                OPENSSL_free(buffer);
index a2e2475..bcb99b8 100644 (file)
@@ -3969,16 +3969,20 @@ tls1_process_heartbeat(SSL *s)
        unsigned int payload;
        unsigned int padding = 16; /* Use minimum padding */
 
-       /* Read type and payload length first */
-       hbtype = *p++;
-       n2s(p, payload);
-       pl = p;
-
        if (s->msg_callback)
                s->msg_callback(0, s->version, TLS1_RT_HEARTBEAT,
                        &s->s3->rrec.data[0], s->s3->rrec.length,
                        s, s->msg_callback_arg);
 
+       /* Read type and payload length first */
+       if (1 + 2 + 16 > s->s3->rrec.length)
+               return 0; /* silently discard */
+       hbtype = *p++;
+       n2s(p, payload);
+       if (1 + 2 + payload + 16 > s->s3->rrec.length)
+               return 0; /* silently discard per RFC 6520 sec. 4 */
+       pl = p;
+
        if (hbtype == TLS1_HB_REQUEST)
                {
                unsigned char *buffer, *bp;