Fix data loss in unsigned int cast in PK
This patch introduces some additional checks in the PK module for 64-bit
systems only. The problem is that the API functions in the PK
abstraction accept a size_t value for the hashlen, while the RSA module
accepts an unsigned int for the hashlen. Instead of silently casting
size_t to unsigned int, this change checks whether the hashlen overflows
an unsigned int and returns an error.
diff --git a/library/pk.c b/library/pk.c
index 10bd0a5..8d13bc5 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -29,6 +29,8 @@
#include "mbedtls/pk.h"
#include "mbedtls/pk_internal.h"
+#include "mbedtls/bignum.h"
+
#if defined(MBEDTLS_RSA_C)
#include "mbedtls/rsa.h"
#endif
@@ -39,6 +41,8 @@
#include "mbedtls/ecdsa.h"
#endif
+#include <limits.h>
+
/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
volatile unsigned char *p = v; while( n-- ) *p++ = 0;
@@ -209,6 +213,11 @@
int ret;
const mbedtls_pk_rsassa_pss_options *pss_opts;
+#if defined(MBEDTLS_HAVE_INT64)
+ if( md_alg == MBEDTLS_MD_NONE && UINT_MAX < hash_len )
+ return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+#endif /* MBEDTLS_HAVE_INT64 */
+
if( options == NULL )
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
@@ -232,7 +241,7 @@
return( 0 );
#else
return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );
-#endif
+#endif /* MBEDTLS_RSA_C && MBEDTLS_PKCS1_V21 */
}
/* General case: no options */