Patch "fs/9p: Compare qid.path in v9fs_test_inode" has been added to the 4.9-stable tree

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

fs/9p: Compare qid.path in v9fs_test_inode

to the 4.9-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:
fs-9p-compare-qid.path-in-v9fs_test_inode.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Tuomas Tynkkynen <[email protected]>
Date: Wed, 6 Sep 2017 17:59:07 +0300
Subject: fs/9p: Compare qid.path in v9fs_test_inode

From: Tuomas Tynkkynen <[email protected]>

commit 8ee031631546cf2f7859cc69593bd60bbdd70b46 upstream.

Commit fd2421f54423 ("fs/9p: When doing inode lookup compare qid details and inode mode bits.") transformed v9fs_qid_iget() to use iget5_locked() instead of iget_locked(). However, the test() callback is not checking fid.path at all, which means that a lookup in the inode cache can now accidentally locate a completely wrong inode from the same inode hash bucket if the other fields (qid.type and qid.version) match.

---
 fs/9p/vfs_inode.c      |    3 +++
 fs/9p/vfs_inode_dotl.c |    3 +++
 2 files changed, 6 insertions(+)

@@ -483,6 +483,9 @@ static int v9fs_test_inode(struct inode
 
 	if (v9inode->qid.type != st->qid.type)
 		return 0;
+
+	if (v9inode->qid.path != st->qid.path)
+		return 0;
 	return 1;
 }
 

@@ -87,6 +87,9 @@ static int v9fs_test_inode_dotl(struct i
 
 	if (v9inode->qid.type != st->qid.type)
 		return 0;
+
+	if (v9inode->qid.path != st->qid.path)
+		return 0;
 	return 1;
 }
 

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

queue-4.9/fs-9p-compare-qid.path-in-v9fs_test_inode.patch