From f15c99f4d4a96b692bdbb6f343c9112f2fa5a8ed Mon Sep 17 00:00:00 2001 From: "Guy Leaver (guleaver)" Date: Fri, 7 Aug 2015 15:45:21 +0100 Subject: Fix seg fault with 0 p val in SKE If a client receives a ServerKeyExchange for an anon DH ciphersuite with the value of p set to 0 then a seg fault can occur. This commits adds a test to reject p, g and pub key parameters that have a 0 value (in accordance with RFC 5246) The security vulnerability only affects master and 1.0.2, but the fix is additionally applied to 1.0.1 for additional confidence. CVE-2015-1794 Reviewed-by: Richard Levitte Reviewed-by: Matt Caswell --- ssl/s3_clnt.c | 16 ++++++++++++++++ ssl/ssl.h | 3 +++ ssl/ssl_err.c | 3 +++ 3 files changed, 22 insertions(+) diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c index 35ad121..c89564b 100644 --- a/ssl/s3_clnt.c +++ b/ssl/s3_clnt.c @@ -1624,6 +1624,12 @@ int ssl3_get_key_exchange(SSL *s) } p += i; + if (BN_is_zero(dh->p)) { + SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_BAD_DH_P_VALUE); + goto f_err; + } + + if (2 > n - param_len) { SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_LENGTH_TOO_SHORT); goto f_err; @@ -1644,6 +1650,11 @@ int ssl3_get_key_exchange(SSL *s) } p += i; + if (BN_is_zero(dh->g)) { + SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_BAD_DH_G_VALUE); + goto f_err; + } + if (2 > n - param_len) { SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_LENGTH_TOO_SHORT); goto f_err; @@ -1665,6 +1676,11 @@ int ssl3_get_key_exchange(SSL *s) p += i; n -= param_len; + if (BN_is_zero(dh->pub_key)) { + SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_BAD_DH_PUB_KEY_VALUE); + goto f_err; + } + # ifndef OPENSSL_NO_RSA if (alg_a & SSL_aRSA) pkey = diff --git a/ssl/ssl.h b/ssl/ssl.h index d2ab0c0..d9657eb 100644 --- a/ssl/ssl.h +++ b/ssl/ssl.h @@ -2465,8 +2465,11 @@ void ERR_load_SSL_strings(void); # define SSL_R_BAD_DATA_RETURNED_BY_CALLBACK 106 # define SSL_R_BAD_DECOMPRESSION 107 # define SSL_R_BAD_DH_G_LENGTH 108 +# define SSL_R_BAD_DH_G_VALUE 375 # define SSL_R_BAD_DH_PUB_KEY_LENGTH 109 +# define SSL_R_BAD_DH_PUB_KEY_VALUE 393 # define SSL_R_BAD_DH_P_LENGTH 110 +# define SSL_R_BAD_DH_P_VALUE 395 # define SSL_R_BAD_DIGEST_LENGTH 111 # define SSL_R_BAD_DSA_SIGNATURE 112 # define SSL_R_BAD_ECC_CERT 304 diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c index 88621b7..26f149e 100644 --- a/ssl/ssl_err.c +++ b/ssl/ssl_err.c @@ -369,8 +369,11 @@ static ERR_STRING_DATA SSL_str_reasons[] = { "bad data returned by callback"}, {ERR_REASON(SSL_R_BAD_DECOMPRESSION), "bad decompression"}, {ERR_REASON(SSL_R_BAD_DH_G_LENGTH), "bad dh g length"}, + {ERR_REASON(SSL_R_BAD_DH_G_VALUE), "bad dh g value"}, {ERR_REASON(SSL_R_BAD_DH_PUB_KEY_LENGTH), "bad dh pub key length"}, + {ERR_REASON(SSL_R_BAD_DH_PUB_KEY_VALUE), "bad dh pub key value"}, {ERR_REASON(SSL_R_BAD_DH_P_LENGTH), "bad dh p length"}, + {ERR_REASON(SSL_R_BAD_DH_P_VALUE), "bad dh p value"}, {ERR_REASON(SSL_R_BAD_DIGEST_LENGTH), "bad digest length"}, {ERR_REASON(SSL_R_BAD_DSA_SIGNATURE), "bad dsa signature"}, {ERR_REASON(SSL_R_BAD_ECC_CERT), "bad ecc cert"}, -- 1.7.12.1