Add a missing buffer size check

This commit is contained in:
Krzysztof Stachowiak 2018-03-20 14:09:53 +01:00 committed by Krzysztof Stachowiak
parent f8ba5cf8e9
commit 444678ea8b

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@ -2511,9 +2511,42 @@ static int ssl_parse_certificate_request( mbedtls_ssl_context *ssl )
// TODO: should check the signature part against our pk_key though
size_t sig_alg_len = ( ( buf[mbedtls_ssl_hs_hdr_len( ssl ) + 1 + n] << 8 )
| ( buf[mbedtls_ssl_hs_hdr_len( ssl ) + 2 + n] ) );
#if defined(MBEDTLS_DEBUG_C)
unsigned char* sig_alg;
size_t i;
#endif
/*
* The farthes access in buf is in the loop few lines below:
* sig_alg[i + 1],
* where:
* sig_alg = buf + ...hdr_len + 3 + n,
* max(i) = sig_alg_len - 1.
* Therefore the farthest access is:
* buf[...hdr_len + 3 + n + sig_alg_len - 1 + 1],
* which reduces to:
* buf[...hdr_len + 3 + n + sig_alg_len],
* which is one less than we need the buf to be.
*/
if( ssl->in_hslen <= mbedtls_ssl_hs_hdr_len( ssl ) + 3 + n + sig_alg_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
}
#if defined(MBEDTLS_DEBUG_C)
sig_alg = buf + mbedtls_ssl_hs_hdr_len( ssl ) + 3 + n;
for( i = 0; i < sig_alg_len; i += 2 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Supported Signature Algorithm found: %d"
",%d", sig_alg[i], sig_alg[i + 1] ) );
}
#endif
n += 2 + sig_alg_len;
m += 2;
n += sig_alg_len;
if( ssl->in_hslen < mbedtls_ssl_hs_hdr_len( ssl ) + 2 + n )
{