Add bound check in the client ssl_write_use_srtp_ext

Signed-off-by: Johan Pascal <johan.pascal@belledonne-communications.com>
This commit is contained in:
Johan Pascal 2020-09-22 21:49:40 +02:00
parent aae4d22b16
commit 77696eedac

View file

@ -757,8 +757,10 @@ static int ssl_write_alpn_ext( mbedtls_ssl_context *ssl,
#endif /* MBEDTLS_SSL_ALPN */
#if defined(MBEDTLS_SSL_DTLS_SRTP)
static void ssl_write_use_srtp_ext( mbedtls_ssl_context *ssl,
unsigned char *buf, size_t *olen )
static int ssl_write_use_srtp_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
const unsigned char *end,
size_t *olen )
{
unsigned char *p = buf;
size_t protection_profiles_index = 0, ext_len = 0;
@ -769,14 +771,9 @@ static void ssl_write_use_srtp_ext( mbedtls_ssl_context *ssl,
if( ( ssl->conf->dtls_srtp_profile_list == NULL ) ||
( ssl->conf->dtls_srtp_profile_list_len == 0 ) )
{
return;
return( 0 );
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding use_srtp extension" ) );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP ) & 0xFF );
/* RFC 5764 section 4.1.1
* uint8 SRTPProtectionProfile[2];
*
@ -796,6 +793,18 @@ static void ssl_write_use_srtp_ext( mbedtls_ssl_context *ssl,
*/
ext_len = 2 + 2 * ( ssl->conf->dtls_srtp_profile_list_len ) + 1 + mki_len;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding use_srtp extension" ) );
/* Check there is room in the buffer for the extension + 4 bytes
* - the extension tag (2 bytes)
* - the extension length (2 bytes)
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, ext_len + 4 );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP ) & 0xFF );
*p++ = (unsigned char)( ( ( ext_len & 0xFF00 ) >> 8 ) & 0xFF );
*p++ = (unsigned char)( ext_len & 0xFF );
@ -860,6 +869,8 @@ static void ssl_write_use_srtp_ext( mbedtls_ssl_context *ssl,
* + mki value
*/
*olen = p - buf;
return( 0 );
}
#endif /* MBEDTLS_SSL_DTLS_SRTP */
@ -1387,7 +1398,12 @@ static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
#if defined(MBEDTLS_SSL_DTLS_SRTP)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
ssl_write_use_srtp_ext( ssl, p + 2 + ext_len, &olen );
if( ( ret = ssl_write_use_srtp_ext( ssl, p + 2 + ext_len,
end, &olen ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_use_srtp_ext", ret );
return( ret );
}
ext_len += olen;
}
#endif