From: Theodore Ts'o Subject: [PATCH 2/5] nfs: use file_dentry() Date: Sat, 26 Mar 2016 17:09:57 -0400 Message-ID: <1459026600-9232-3-git-send-email-tytso@mit.edu> References: <1459026600-9232-1-git-send-email-tytso@mit.edu> Cc: dhowells@redhat.com, viro@ZenIV.linux.org.uk, Linux Filesystem Development List , jaegeuk@kernel.org, Miklos Szeredi , Theodore Ts'o , , Al Viro To: Ext4 Developers List Return-path: Received: from imap.thunk.org ([74.207.234.97]:34262 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754130AbcCZVKS (ORCPT ); Sat, 26 Mar 2016 17:10:18 -0400 In-Reply-To: <1459026600-9232-1-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Miklos Szeredi 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 Tested-by: Goldwyn Rodrigues Acked-by: Trond Myklebust Signed-off-by: Theodore Ts'o Cc: # v4.2 Cc: David Howells Cc: Al Viro --- fs/nfs/dir.c | 6 +++--- fs/nfs/inode.c | 2 +- fs/nfs/nfs4file.c | 4 ++-- 3 files changed, 6 insertions(+), 6 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 4bfa7d8..a89d32a 100644 --- 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 86faecf..847b678 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -940,7 +940,7 @@ 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 57ca1c8..2a9ff14 100644 --- 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; -- 2.5.0