[PATCH 4.9 20/64] security/keys: properly zero out sensitive key material in big_key

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason A. Donenfeld <ja...@zx2c4.com>

commit 910801809b2e40a4baedd080ef5d80b4a180e70e upstream.

Error paths forgot to zero out sensitive material, so this patch changes
some kfrees into a kzfrees.

Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com>
Signed-off-by: David Howells <dhowe...@redhat.com>
Reviewed-by: Eric Biggers <ebigge...@gmail.com>
Cc: Herbert Xu <herb...@gondor.apana.org.au>
Cc: Kirill Marinushkin <k.marinush...@gmail.com>
Cc: secur...@kernel.org
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 security/keys/big_key.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/security/keys/big_key.c
+++ b/security/keys/big_key.c
@@ -194,7 +194,7 @@ int big_key_preparse(struct key_preparse
                *path = file->f_path;
                path_get(path);
                fput(file);
-               kfree(data);
+               kzfree(data);
        } else {
                /* Just store the data in a buffer */
                void *data = kmalloc(datalen, GFP_KERNEL);
@@ -210,9 +210,9 @@ int big_key_preparse(struct key_preparse
 err_fput:
        fput(file);
 err_enckey:
-       kfree(enckey);
+       kzfree(enckey);
 error:
-       kfree(data);
+       kzfree(data);
        return ret;
 }
 
@@ -226,7 +226,7 @@ void big_key_free_preparse(struct key_pr
 
                path_put(path);
        }
-       kfree(prep->payload.data[big_key_data]);
+       kzfree(prep->payload.data[big_key_data]);
 }
 
 /*
@@ -258,7 +258,7 @@ void big_key_destroy(struct key *key)
                path->mnt = NULL;
                path->dentry = NULL;
        }
-       kfree(key->payload.data[big_key_data]);
+       kzfree(key->payload.data[big_key_data]);
        key->payload.data[big_key_data] = NULL;
 }
 
@@ -326,7 +326,7 @@ long big_key_read(const struct key *key,
 err_fput:
                fput(file);
 error:
-               kfree(data);
+               kzfree(data);
        } else {
                ret = datalen;
                if (copy_to_user(buffer, key->payload.data[big_key_data],