From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751837AbcF2Iyb (ORCPT ); Wed, 29 Jun 2016 04:54:31 -0400 Received: from mail-wm0-f45.google.com ([74.125.82.45]:35068 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750921AbcF2Iy2 (ORCPT ); Wed, 29 Jun 2016 04:54:28 -0400 From: Miklos Szeredi To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alessio Igor Bogani , Eric Van Hensbergen Subject: [PATCH] 9p: use file_dentry() Date: Wed, 29 Jun 2016 10:54:23 +0200 Message-Id: <1467190463-9906-1-git-send-email-mszeredi@redhat.com> X-Mailer: git-send-email 2.5.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v9fs may be used as lower layer of overlayfs and accessing f_path.dentry can lead to a crash. In this case it's a NULL pointer dereference in p9_fid_create(). Fix by replacing direct access of file->f_path.dentry with the file_dentry() accessor, which will always return a native object. Reported-by: Alessio Igor Bogani Signed-off-by: Miklos Szeredi Tested-by: Alessio Igor Bogani Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay") Cc: --- fs/9p/vfs_file.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c index b84c291ba1eb..d7b78d531e63 100644 --- a/fs/9p/vfs_file.c +++ b/fs/9p/vfs_file.c @@ -74,7 +74,7 @@ int v9fs_file_open(struct inode *inode, struct file *file) v9fs_proto_dotu(v9ses)); fid = file->private_data; if (!fid) { - fid = v9fs_fid_clone(file->f_path.dentry); + fid = v9fs_fid_clone(file_dentry(file)); if (IS_ERR(fid)) return PTR_ERR(fid); @@ -100,7 +100,7 @@ int v9fs_file_open(struct inode *inode, struct file *file) * because we want write after unlink usecase * to work. */ - fid = v9fs_writeback_fid(file->f_path.dentry); + fid = v9fs_writeback_fid(file_dentry(file)); if (IS_ERR(fid)) { err = PTR_ERR(fid); mutex_unlock(&v9inode->v_mutex); @@ -516,7 +516,7 @@ v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma) * because we want write after unlink usecase * to work. */ - fid = v9fs_writeback_fid(filp->f_path.dentry); + fid = v9fs_writeback_fid(file_dentry(filp)); if (IS_ERR(fid)) { retval = PTR_ERR(fid); mutex_unlock(&v9inode->v_mutex); -- 2.5.5