NFS: Fix an Oops in encode_lookup()

It doesn't look as if the NFS file name limit is being initialised correctly
in the struct nfs_server. Make sure that we limit whatever is being set in
nfs_probe_fsinfo() and nfs_init_server().

Also ensure that readdirplus and nfs4_path_walk respect our file name
limits.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/nfs/client.c

@@ -588,16 +588,6 @@ static int nfs_init_server(struct nfs_server *server, const struct nfs_mount_dat
 	server->namelen  = data->namlen;
 	/* Create a client RPC handle for the NFSv3 ACL management interface */
 	nfs_init_server_aclclient(server);
-	if (clp->cl_nfsversion == 3) {
-		if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
-			server->namelen = NFS3_MAXNAMLEN;
-		if (!(data->flags & NFS_MOUNT_NORDIRPLUS))
-			server->caps |= NFS_CAP_READDIRPLUS;
-	} else {
-		if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
-			server->namelen = NFS2_MAXNAMLEN;
-	}
-
 	dprintk("<-- nfs_init_server() = 0 [new %p]\n", clp);
 	return 0;
 
@@ -794,6 +784,16 @@ struct nfs_server *nfs_create_server(const struct nfs_mount_data *data,
 	error = nfs_probe_fsinfo(server, mntfh, &fattr);
 	if (error < 0)
 		goto error;
+	if (server->nfs_client->rpc_ops->version == 3) {
+		if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
+			server->namelen = NFS3_MAXNAMLEN;
+		if (!(data->flags & NFS_MOUNT_NORDIRPLUS))
+			server->caps |= NFS_CAP_READDIRPLUS;
+	} else {
+		if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
+			server->namelen = NFS2_MAXNAMLEN;
+	}
+
 	if (!(fattr.valid & NFS_ATTR_FATTR)) {
 		error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr);
 		if (error < 0) {
@@ -984,6 +984,9 @@ struct nfs_server *nfs4_create_server(const struct nfs4_mount_data *data,
 	if (error < 0)
 		goto error;
 
+	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
+		server->namelen = NFS4_MAXNAMLEN;
+
 	BUG_ON(!server->nfs_client);
 	BUG_ON(!server->nfs_client->rpc_ops);
 	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);
@@ -1056,6 +1059,9 @@ struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,
 	if (error < 0)
 		goto error;
 
+	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
+		server->namelen = NFS4_MAXNAMLEN;
+
 	dprintk("Referral FSID: %llx:%llx\n",
 		(unsigned long long) server->fsid.major,
 		(unsigned long long) server->fsid.minor);
@@ -1115,6 +1121,9 @@ struct nfs_server *nfs_clone_server(struct nfs_server *source,
 	if (error < 0)
 		goto out_free_server;
 
+	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
+		server->namelen = NFS4_MAXNAMLEN;
+
 	dprintk("Cloned FSID: %llx:%llx\n",
 		(unsigned long long) server->fsid.major,
 		(unsigned long long) server->fsid.minor);

fs/nfs/dir.c

@@ -1162,6 +1162,8 @@ static struct dentry *nfs_readdir_lookup(nfs_readdir_descriptor_t *desc)
 	}
 	if (!desc->plus || !(entry->fattr->valid & NFS_ATTR_FATTR))
 		return NULL;
+	if (name.len > NFS_SERVER(dir)->namelen)
+		return NULL;
 	/* Note: caller is already holding the dir->i_mutex! */
 	dentry = d_alloc(parent, &name);
 	if (dentry == NULL)

fs/nfs/getroot.c

@@ -175,6 +175,9 @@ next_component:
 		path++;
 	name.len = path - (const char *) name.name;
 
+	if (name.len > NFS4_MAXNAMLEN)
+		return -ENAMETOOLONG;
+
 eat_dot_dir:
 	while (*path == '/')
 		path++;