Fix potential memory corruption in calls to gnutls function on 64 bit arch

[#60 state:resolved]

Signed-off-by: Matt Colyer <matt@colyer.name>

1 files changed, 5 insertions, 3 deletions

diff --git a/src/lockdown.c b/src/lockdown.c
index bc430c9..88ab7b0 100644
--- a/src/lockdown.c
+++ b/src/lockdown.c
@@ -954,10 +954,12 @@ lockdownd_error_t lockdownd_gen_pair_cert(gnutls_datum_t public_key, gnutls_datu
 
                                 if (LOCKDOWN_E_SUCCESS == ret) {
                                         /* if everything went well, export in PEM format */
+                                        size_t export_size = 0;
                                         gnutls_datum_t dev_pem = { NULL, 0 };
-                                        gnutls_x509_crt_export(dev_cert, GNUTLS_X509_FMT_PEM, NULL, &dev_pem.size);
-                                        dev_pem.data = gnutls_malloc(dev_pem.size);
-                                        gnutls_x509_crt_export(dev_cert, GNUTLS_X509_FMT_PEM, dev_pem.data, &dev_pem.size);
+                                        gnutls_x509_crt_export(dev_cert, GNUTLS_X509_FMT_PEM, NULL, &export_size);
+                                        dev_pem.data = gnutls_malloc(export_size);
+                                        gnutls_x509_crt_export(dev_cert, GNUTLS_X509_FMT_PEM, dev_pem.data, &export_size);
+                                        dev_pem.size = export_size;
 
                                         gnutls_datum_t pem_root_cert = { NULL, 0 };
                                         gnutls_datum_t pem_host_cert = { NULL, 0 };