From 61e72d761c945e128ca13599a98a187ac23650dd Mon Sep 17 00:00:00 2001 From: "Guy Leaver (guleaver)" Date: Fri, 7 Aug 2015 15:45:21 +0100 Subject: [PATCH] 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 --- include/openssl/ssl.h | 3 +++ ssl/s3_clnt.c | 16 ++++++++++++++++ ssl/ssl_err.c | 3 +++ 3 files changed, 22 insertions(+) diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h index 4958e890b6..28c2fb9866 100644 --- a/include/openssl/ssl.h +++ b/include/openssl/ssl.h @@ -2107,8 +2107,11 @@ 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/s3_clnt.c b/ssl/s3_clnt.c index cd6918aa6b..1661b0ef8c 100644 --- a/ssl/s3_clnt.c +++ b/ssl/s3_clnt.c @@ -1693,6 +1693,12 @@ 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; @@ -1713,6 +1719,11 @@ 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; @@ -1734,6 +1745,11 @@ 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; + } + if (!ssl_security(s, SSL_SECOP_TMP_DH, DH_security_bits(dh), 0, dh)) { al = SSL_AD_HANDSHAKE_FAILURE; SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_DH_KEY_TOO_SMALL); diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c index 2e1497bd85..21836d831d 100644 --- a/ssl/ssl_err.c +++ b/ssl/ssl_err.c @@ -345,8 +345,11 @@ 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"}, -- 2.25.1