Add a missing buffer size check
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 5a49d53..a66cbb0 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2511,9 +2511,42 @@
// 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 )
{