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>

3 files changed, 24 insertions, 10 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index a49f9feff776..a204484072f3 100644
--- a/fs/nfs/client.c
+++ b/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);
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ea97408e423e..e4a04d16b8b0 100644
--- a/fs/nfs/dir.c
+++ b/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)
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index d1cbf0a0fbb2..522e5ad4d8ad 100644
--- a/fs/nfs/getroot.c
+++ b/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++;