From: Tim Hudson <tjh@cryptsoft.com>
Date: Sat, 26 Apr 2014 15:55:47 +0000 (+1000)
Subject: safety check to ensure we dont send out beyond the users buffer
X-Git-Tag: master-post-reformat~823
X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=c388d8b40cb9a3cb67401455509c1497a1a1fcb4

safety check to ensure we dont send out beyond the users buffer
---

diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.c
index d601a18171..41193bb7d1 100644
--- a/ssl/s3_pkt.c
+++ b/ssl/s3_pkt.c
@@ -816,6 +816,21 @@ int ssl3_write_bytes(SSL *s, int type, const void *buf_, int len)
 		return tot;
 		}
 
+	/* ensure that if we end up with a smaller value of data to write 
+	 * out than the the original len from a write which didn't complete 
+	 * for non-blocking I/O and also somehow ended up avoiding 
+	 * the check for this in ssl3_write_pending/SSL_R_BAD_WRITE_RETRY as
+	 * it must never be possible to end up with (len-tot) as a large
+	 * number that will then promptly send beyond the end of the users
+	 * buffer ... so we trap and report the error in a way the user
+	 * will notice
+	 */
+	if ( len < tot)
+		{
+		SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_BAD_LENGTH);
+		return(-1);
+		}
+
 	n=(len-tot);
 	for (;;)
 		{