From 33d5ba862939ff8db70a9e36fc9a326fab3e8d98 Mon Sep 17 00:00:00 2001 From: Emilia Kasper Date: Mon, 1 Dec 2014 15:04:02 +0100 Subject: [PATCH] Reject elliptic curve lists of odd lengths. The Supported Elliptic Curves extension contains a vector of NamedCurves of 2 bytes each, so the total length must be even. Accepting odd-length lists was observed to lead to a non-exploitable one-byte out-of-bounds read in the latest development branches (1.0.2 and master). Released versions of OpenSSL are not affected. Thanks to Felix Groebert of the Google Security Team for reporting this issue. Reviewed-by: Matt Caswell --- ssl/t1_lib.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index e0f28d254b..c5c8bb95f3 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -2155,7 +2155,9 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char ellipticcurvelist_length += (*(sdata++)); if (ellipticcurvelist_length != size - 2 || - ellipticcurvelist_length < 1) + ellipticcurvelist_length < 1 || + /* Each NamedCurve is 2 bytes. */ + ellipticcurvelist_length & 1) { *al = TLS1_AD_DECODE_ERROR; return 0; -- 2.25.1