[openssl-commits] [openssl] OpenSSL_1_1_0-stable update

[Matt Caswell]

The branch OpenSSL_1_1_0-stable has been updated
       via  1b261954028925c1e2c329928938dacacf0bb6c0 (commit)
      from  36d2517a97f6020049116492b4d5491d177e629c (commit)


- Log -----------------------------------------------------------------
commit 1b261954028925c1e2c329928938dacacf0bb6c0
Author: Matt Caswell <matt at openssl.org>
Date:   Fri May 11 10:28:47 2018 +0100

    Don't memcpy the contents of an empty fragment
    
    In DTLS if we have buffered a fragment for a zero length message (e.g.
    ServerHelloDone) then, when we unbuffered the fragment, we were attempting
    to memcpy the contents of the fragment which is zero length and a NULL
    pointer. This is undefined behaviour. We should check first whether we
    have a zero length fragment.
    
    Fixes a travis issue.
    
    [extended tests]
    
    Reviewed-by: Rich Salz <rsalz at openssl.org>
    (Merged from https://github.com/openssl/openssl/pull/6224)

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

Summary of changes:
 ssl/statem/statem_dtls.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ssl/statem/statem_dtls.c b/ssl/statem/statem_dtls.c
index 6b80620..5b34425 100644
--- a/ssl/statem/statem_dtls.c
+++ b/ssl/statem/statem_dtls.c
@@ -493,7 +493,8 @@ static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
 
         al = dtls1_preprocess_fragment(s, &frag->msg_header);
 
-        if (al == 0) {          /* no alert */
+        /* al will be 0 if no alert */
+        if (al == 0  && frag->msg_header.frag_len > 0) {
             unsigned char *p =
                 (unsigned char *)s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
             memcpy(&p[frag->msg_header.frag_off], frag->fragment,