agent: Fix alignment problem with the second passphrase struct.

* agent/genkey.c (agent_ask_new_passphrase): Use a separate malloc for
PI2.  Check return value of the malloc function.
* agent/command-ssh.c (ssh_identity_register): Use a separate malloc
for PI2.  Wipe PI2.
--

For whatever stupid reasons I once allocated only one memory area and
split that into PI and PI2.  This is actually a common pattern with
malloc but here we used a made up object size and do not take the
extra alignment required into account.  One of these not yet hit by
a (sig)bus PC/VAX hacker bugs.

Instead of trying to fix the alignment, it is better to use a second
calloc for the second struct.

GnuPG-bug-id: 2112
Signed-off-by: Werner Koch <[email protected]>

2 files changed, 23 insertions, 5 deletions

diff --git a/agent/command-ssh.c b/agent/command-ssh.c
index 8be125503..0aa0098f2 100644
--- a/agent/command-ssh.c
+++ b/agent/command-ssh.c
@@ -3070,7 +3070,8 @@ ssh_identity_register (ctrl_t ctrl, ssh_key_type_spec_t *spec,
   char *comment = NULL;
   char *key_fpr = NULL;
   const char *initial_errtext = NULL;
-  struct pin_entry_info_s *pi = NULL, *pi2;
+  struct pin_entry_info_s *pi = NULL;
+  struct pin_entry_info_s *pi2 = NULL;
 
   err = ssh_key_grip (key, key_grip_raw);
   if (err)
@@ -3101,13 +3102,18 @@ ssh_identity_register (ctrl_t ctrl, ssh_key_type_spec_t *spec,
       goto out;
     }
 
-  pi = gcry_calloc_secure (2, sizeof (*pi) + MAX_PASSPHRASE_LEN + 1);
+  pi = gcry_calloc_secure (1, sizeof (*pi) + MAX_PASSPHRASE_LEN + 1);
   if (!pi)
     {
       err = gpg_error_from_syserror ();
       goto out;
     }
-  pi2 = pi + (sizeof *pi + MAX_PASSPHRASE_LEN + 1);
+  pi2 = gcry_calloc_secure (1, sizeof (*pi2) + MAX_PASSPHRASE_LEN + 1);
+  if (!pi2)
+    {
+      err = gpg_error_from_syserror ();
+      goto out;
+    }
   pi->max_length = MAX_PASSPHRASE_LEN + 1;
   pi->max_tries = 1;
   pi->with_repeat = 1;
@@ -3155,6 +3161,9 @@ ssh_identity_register (ctrl_t ctrl, ssh_key_type_spec_t *spec,
 
 
  out:
+  if (pi2 && pi2->max_length)
+    wipememory (pi2->pin, pi2->max_length);
+  xfree (pi2);
   if (pi && pi->max_length)
     wipememory (pi->pin, pi->max_length);
   xfree (pi);
diff --git a/agent/genkey.c b/agent/genkey.c
index 13858cae3..e8195c200 100644
--- a/agent/genkey.c
+++ b/agent/genkey.c
@@ -374,8 +374,16 @@ agent_ask_new_passphrase (ctrl_t ctrl, const char *prompt,
 	return err;
     }
 
-  pi = gcry_calloc_secure (2, sizeof (*pi) + MAX_PASSPHRASE_LEN + 1);
-  pi2 = pi + (sizeof *pi + MAX_PASSPHRASE_LEN + 1);
+  pi = gcry_calloc_secure (1, sizeof (*pi) + MAX_PASSPHRASE_LEN + 1);
+  if (!pi)
+    return gpg_error_from_syserror ();
+  pi2 = gcry_calloc_secure (1, sizeof (*pi2) + MAX_PASSPHRASE_LEN + 1);
+  if (!pi2)
+    {
+      err = gpg_error_from_syserror ();
+      xfree (pi2);
+      return err;
+    }
   pi->max_length = MAX_PASSPHRASE_LEN + 1;
   pi->max_tries = 3;
   pi->with_qualitybar = 1;
@@ -422,6 +430,7 @@ agent_ask_new_passphrase (ctrl_t ctrl, const char *prompt,
     }
 
   xfree (initial_errtext);
+  xfree (pi2);
   xfree (pi);
   return err;
 }