From 83a1d4b2011ff3a7798250902bdacbca6e1766c0 Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Fri, 14 Oct 2016 11:49:06 +0100 Subject: [PATCH] Fix length check writing status request extension The status request extension did not correctly check its length, meaning that writing the extension could go 2 bytes beyond the buffer size. In practice this makes little difference because, due to logic in buffer.c the buffer is actually over allocated by approximately 5k! Issue reported by Guido Vranken. Reviewed-by: Rich Salz --- ssl/t1_lib.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 7831046b92..e53c76e0b3 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -1479,7 +1479,14 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *buf, } else extlen = 0; - if ((long)(limit - ret - 7 - extlen - idlen) < 0) + /* + * 2 bytes for status request type + * 2 bytes for status request len + * 1 byte for OCSP request type + * 2 bytes for length of ids + * 2 bytes for length of extensions + */ + if ((long)(limit - ret - 9 - extlen - idlen) < 0) return NULL; s2n(TLSEXT_TYPE_status_request, ret); if (extlen + idlen > 0xFFF0) -- 2.25.1