Fix potential integer overflow parsing DER CRL
This patch prevents a potential signed integer overflow during the
CRL version verification checks.
diff --git a/ChangeLog b/ChangeLog
index d3d1e0b..58ee285 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -13,6 +13,10 @@
Found by redplait #590
* Add MBEDTLS_MPI_CHK to check for error value of mbedtls_mpi_fill_random.
Reported and fix suggested by guidovranken in #740
+ * Fix a potential integer overflow in the version verification for DER
+ encoded X509 CRLs. The overflow would enable maliciously constructed CRLs
+ to bypass the version verification check. Found by Peng Li/Yueh-Hsun Lin,
+ KNOX Security, Samsung Research America
Features
* Add the functions mbedtls_platform_setup() and mbedtls_platform_teardown()
diff --git a/library/x509_crl.c b/library/x509_crl.c
index 76c49f1..55d12ac 100644
--- a/library/x509_crl.c
+++ b/library/x509_crl.c
@@ -352,14 +352,14 @@
return( ret );
}
- crl->version++;
-
- if( crl->version > 2 )
+ if( crl->version < 0 || crl->version > 1 )
{
mbedtls_x509_crl_free( crl );
return( MBEDTLS_ERR_X509_UNKNOWN_VERSION );
}
+ crl->version++;
+
if( ( ret = mbedtls_x509_get_sig_alg( &crl->sig_oid, &sig_params1,
&crl->sig_md, &crl->sig_pk,
&crl->sig_opts ) ) != 0 )