disk/cryptodisk: Wipe the passphrase from memory

Switching to another EFI boot application while there are secrets in
RAM is dangerous, because not all firmware is wiping memory on free.

To reduce the attack surface, wipe the passphrase acquired when
unlocking an encrypted volume.

Signed-off-by: Maxim Suhanov <dfirblog@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 544a30d61517ce1d3076a9aa35b40747a8b696e4..7065bcdcb54751c37c22747424be4cad5bc5901c 100644 (file)
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -1302,6 +1302,7 @@ grub_cryptodisk_scan_device_real (const char *name,
 
   if (askpass)
     {
+      grub_memset (cargs->key_data, 0, cargs->key_len);
       cargs->key_len = 0;
       grub_free (cargs->key_data);
     }