Simplify bounds check in ssl_write_certificate_request
It is sufficient to check for the strongest limit only. Using a smaller
type ensures there is no overflow (assuming size_t is at least 32 bits).
Fixes #2916
Signed-off-by: irwir <irwir@users.noreply.github.com>
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 469c67e..07fb2fa 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2841,7 +2841,7 @@
int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
ssl->handshake->ciphersuite_info;
- size_t dn_size, total_dn_size; /* excluding length bytes */
+ uint16_t dn_size, total_dn_size; /* excluding length bytes */
size_t ct_len, sa_len; /* including length bytes */
unsigned char *buf, *p;
const unsigned char * const end = ssl->out_msg + MBEDTLS_SSL_OUT_CONTENT_LEN;
@@ -2969,11 +2969,11 @@
while( crt != NULL && crt->version != 0 )
{
- dn_size = crt->subject_raw.len;
+ /* It follows from RFC 5280 A.1 that this length
+ * can be represented in at most 11 bits. */
+ dn_size = (uint16_t) crt->subject_raw.len;
- if( end < p ||
- (size_t)( end - p ) < dn_size ||
- (size_t)( end - p ) < 2 + dn_size )
+ if( end < p || (size_t)( end - p ) < 2 + (size_t) dn_size )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "skipping CAs: buffer too short" ) );
break;