NFS: Fix potential buffer overflowin nfs_sysfs_link_rpc_client()

name is char[64] where the size of clnt->cl_program->name remains
unknown. Invoking strcat() directly will also lead to potential buffer
overflow. Change them to strscpy() and strncat() to fix potential
issues.

Signed-off-by: Zichen Xie <zichenxie0106@gmail.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Author: Gax-c

fs/nfs/sysfs.c

@@ -280,9 +280,9 @@ void nfs_sysfs_link_rpc_client(struct nfs_server *server,
 	char name[RPC_CLIENT_NAME_SIZE];
 	int ret;
 
-	strcpy(name, clnt->cl_program->name);
-	strcat(name, uniq ? uniq : "");
-	strcat(name, "_client");
+	strscpy(name, clnt->cl_program->name, sizeof(name));
+	strncat(name, uniq ? uniq : "", sizeof(name) - strlen(name) - 1);
+	strncat(name, "_client", sizeof(name) - strlen(name) - 1);
 
 	ret = sysfs_create_link_nowarn(&server->kobj,
 						&clnt->cl_sysfs->kobject, name);