_gnutls_x509_write_uint32: ensure we prepend leading zero when writing

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

diff --git a/lib/x509/mpi.c b/lib/x509/mpi.c
index 2e7cdc28022c75ca28d2eb2b1ec360bd3ea5c3d4..2bb3e54aaa6fd39ac86bb572ad8c6625b374178d 100644 (file)
--- a/lib/x509/mpi.c
+++ b/lib/x509/mpi.c
@@ -28,6 +28,7 @@
 #include "common.h"
 #include "x509_int.h"
 #include <num.h>
+#include <limits.h>
 
 /* Reads an Integer from the DER encoded data
  */
@@ -319,12 +320,17 @@ _gnutls_x509_read_uint(ASN1_TYPE node, const char *value,
 int
 _gnutls_x509_write_uint32(ASN1_TYPE node, const char *value, uint32_t num)
 {
-       uint8_t tmpstr[4];
+       uint8_t tmpstr[5];
        int result;
 
-       _gnutls_write_uint32(num, tmpstr);
+       tmpstr[0] = 0;
+       _gnutls_write_uint32(num, tmpstr+1);
 
-       result = asn1_write_value(node, value, tmpstr, 4);
+       if (tmpstr[1] > SCHAR_MAX) {
+               result = asn1_write_value(node, value, tmpstr, 5);
+       } else {
+               result = asn1_write_value(node, value, tmpstr+1, 4);
+       }
 
        if (result != ASN1_SUCCESS) {
                gnutls_assert();