Patch "9p: use file_dentry()" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

9p: use file_dentry()

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
9p-use-file_dentry.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Miklos Szeredi <[email protected]>
Date: Wed, 29 Jun 2016 10:54:23 +0200
Subject: 9p: use file_dentry()

From: Miklos Szeredi <[email protected]>

commit b403f0e37a11f84f7ceaf40b0075499e5bcfd220 upstream.

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.

---
 fs/9p/vfs_file.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

@@ -74,7 +74,7 @@ int v9fs_file_open(struct inode *inode,
 					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,
 		 * 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, s
 		 * 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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/9p-use-file_dentry.patch
queue-4.6/locks-use-file_inode.patch