Fix return code for truncated DTLS fragment.

Previously, a truncated DTLS fragment in
|dtls1_process_out_of_seq_message| would cause *ok to be cleared, but
the return value would still be the number of bytes read. This would
cause |dtls1_get_message| not to consider it an error and it would
continue processing as normal until the calling function noticed that
*ok was zero.

I can't see an exploit here because |dtls1_get_message| uses
|s->init_num| as the length, which will always be zero from what I can
see.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>

diff --git a/ssl/d1_both.c b/ssl/d1_both.c
index 4d8d2d15bacabf1daf4d4b508e6f0ca50c69f6fb..29df26e99a35f054081240dfae844f40e297fd5a 100644 (file)
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.c
@@ -776,7 +776,9 @@ dtls1_process_out_of_seq_message(SSL *s, struct hm_header_st* msg_hdr, int *ok)
                        /* read the body of the fragment (header has already been read */
                        i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
                                frag->fragment,frag_len,0);
                        /* read the body of the fragment (header has already been read */
                        i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
                                frag->fragment,frag_len,0);

-                       if (i<=0 || (unsigned long)i!=frag_len)
+                       if ((unsigned long)i!=frag_len)
+                               i = -1;
+                       if (i<=0)

                                goto err;
                        }
 
                                goto err;
                        }