NFS: Fix potential buffer overflowin nfs_sysfs_link_rpc_client()

JIRA: https://issues.redhat.com/browse/RHEL-81064
CVE: CVE-2024-54456

commit 49fd4e3
Author: Zichen Xie <zichenxie0106@gmail.com>
Date:   Wed Dec 18 00:13:12 2024 +0800

    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>

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

Author: CKI Backport Bot

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);