ecryptfs: fix string overflow on long cipher names

Passing a cipher name > 32 chars on mount results in an overflow when the
cipher name is printed, because the last character in the struct
ecryptfs_key_tfm's cipher_name string was never zeroed.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Acked-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ecryptfs/crypto.c

@@ -1847,6 +1847,7 @@ ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
 	mutex_init(&tmp_tfm->key_tfm_mutex);
 	strncpy(tmp_tfm->cipher_name, cipher_name,
 		ECRYPTFS_MAX_CIPHER_NAME_SIZE);
+	tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
 	tmp_tfm->key_size = key_size;
 	rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
 					 tmp_tfm->cipher_name,