From 80164741e181a87ae18fa91a07f7201931b4d097 Mon Sep 17 00:00:00 2001 From: Andres AG Date: Thu, 9 Mar 2017 16:16:11 +0000 Subject: [PATCH] Fix potential integer overflow parsing DER CRT This patch prevents a potential signed integer overflow during the certificate version verification checks. --- ChangeLog | 3 +++ library/x509_crt.c | 6 +++--- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/ChangeLog b/ChangeLog index 58ee285a5..567e98883 100644 --- a/ChangeLog +++ b/ChangeLog @@ -228,6 +228,9 @@ Bugfix digits. Found and fixed by Guido Vranken. * Fix unlisted DES configuration dependency in some pkparse test cases. Found by inestlerode. #555 + * Fix a potential integer overflow in the version verification for DER + encoded X509 certificates. The overflow would enable maliciously + constructed certificates to bypass the certificate verification check. = mbed TLS 2.4.1 branch released 2016-12-13 diff --git a/library/x509_crt.c b/library/x509_crt.c index 5ec855192..c6209fb40 100644 --- a/library/x509_crt.c +++ b/library/x509_crt.c @@ -748,14 +748,14 @@ static int x509_crt_parse_der_core( mbedtls_x509_crt *crt, const unsigned char * return( ret ); } - crt->version++; - - if( crt->version > 3 ) + if( crt->version < 0 || crt->version > 2 ) { mbedtls_x509_crt_free( crt ); return( MBEDTLS_ERR_X509_UNKNOWN_VERSION ); } + crt->version++; + if( ( ret = mbedtls_x509_get_sig_alg( &crt->sig_oid, &sig_params1, &crt->sig_md, &crt->sig_pk, &crt->sig_opts ) ) != 0 )