nfs: use file_dentry()

commit be62a1a8fd116f5cd9e53726601f970e16e17558 upstream.

NFS may be used as lower layer of overlayfs and accessing f_path.dentry can
lead to a crash.

Fix by replacing direct access of file->f_path.dentry with the
file_dentry() accessor, which will always return a native object.

Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ce5a21861074293ca0968b04d1d13e4406ca93bd..5fc2162afb67207118872e2f0c560fb20381e7ec 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -377,7 +377,7 @@ int nfs_readdir_xdr_filler(struct page **pages, nfs_readdir_descriptor_t *desc,
  again:
        timestamp = jiffies;
        gencount = nfs_inc_attr_generation_counter();
-       error = NFS_PROTO(inode)->readdir(file->f_path.dentry, cred, entry->cookie, pages,
+       error = NFS_PROTO(inode)->readdir(file_dentry(file), cred, entry->cookie, pages,
                                          NFS_SERVER(inode)->dtsize, desc->plus);
        if (error < 0) {
                /* We requested READDIRPLUS, but the server doesn't grok it */
@@ -560,7 +560,7 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
                count++;
 
                if (desc->plus != 0)
-                       nfs_prime_dcache(desc->file->f_path.dentry, entry);
+                       nfs_prime_dcache(file_dentry(desc->file), entry);
 
                status = nfs_readdir_add_to_array(entry, page);
                if (status != 0)
@@ -864,7 +864,7 @@ static bool nfs_dir_mapping_need_revalidate(struct inode *dir)
  */
 static int nfs_readdir(struct file *file, struct dir_context *ctx)
 {
-       struct dentry   *dentry = file->f_path.dentry;
+       struct dentry   *dentry = file_dentry(file);
        struct inode    *inode = d_inode(dentry);
        nfs_readdir_descriptor_t my_desc,
                        *desc = &my_desc;

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 3e2071a177fd029e043b34018b7628d8c6b03309..f714b98cfd744d435238b02713df053a77ee0d34 100644 (file)
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -927,7 +927,7 @@ int nfs_open(struct inode *inode, struct file *filp)
 {
        struct nfs_open_context *ctx;
 
-       ctx = alloc_nfs_open_context(filp->f_path.dentry, filp->f_mode);
+       ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode);
        if (IS_ERR(ctx))
                return PTR_ERR(ctx);
        nfs_file_set_open_context(filp, ctx);

diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index db9b5fea5b3ef12f6eacf36cd2154c2db7d4d9f2..679e003818b1bb8612d8496c589f76570a34b606 100644 (file)
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -26,7 +26,7 @@ static int
 nfs4_file_open(struct inode *inode, struct file *filp)
 {
        struct nfs_open_context *ctx;
-       struct dentry *dentry = filp->f_path.dentry;
+       struct dentry *dentry = file_dentry(filp);
        struct dentry *parent = NULL;
        struct inode *dir;
        unsigned openflags = filp->f_flags;
@@ -57,7 +57,7 @@ nfs4_file_open(struct inode *inode, struct file *filp)
        parent = dget_parent(dentry);
        dir = d_inode(parent);
 
-       ctx = alloc_nfs_open_context(filp->f_path.dentry, filp->f_mode);
+       ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode);
        err = PTR_ERR(ctx);
        if (IS_ERR(ctx))
                goto out;