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Fix seg fault with 0 p val in SKE

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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 <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
This commit is contained in:
Guy Leaver (guleaver) 2015-08-07 15:45:21 +01:00 committed by Matt Caswell
parent 507ea77b82
commit f15c99f4d4
3 changed files with 22 additions and 0 deletions
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16
ssl/s3_clnt.c
View File

@ -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 =

3
ssl/ssl.h
View File

@ -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

3
ssl/ssl_err.c
View File

@ -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"},