diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 51651314b7a6..bd3e025899f7 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -737,6 +737,12 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 		       "password tokens\n", __func__);
 		goto out_free_unlock;
 	}
+	if (s->auth_tok->token.password.session_key_encryption_key_bytes >
+			sizeof(s->auth_tok->token.password.session_key_encryption_key)) {
+		printk(KERN_ERR "Error FNEK key size too large\n");
+		rc = -EINVAL;
+		goto out_free_unlock;
+	}
 
 	md5(s->auth_tok->token.password.session_key_encryption_key,
 	    s->auth_tok->token.password.session_key_encryption_key_bytes,