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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Latchesar Ionkov" <lucho@ionkov.net>,
        "Tuomas Tynkkynen" <tuomas@tuxera.com>,
        "Al Viro" <viro@zeniv.linux.org.uk>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
Message-ID: <lsq.1518322806.126111496@decadent.org.uk>
Subject: [PATCH 3.2 12/79] fs/9p: Compare qid.path in v9fs_test_inode
In-Reply-To: <lsq.1518322802.943358572@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tuomas Tynkkynen <tuomas@tuxera.com>

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.

Fixes: fd2421f54423 ("fs/9p: When doing inode lookup compare qid details and inode mode bits.")
Reviewed-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/9p/vfs_inode.c      | 3 +++
 fs/9p/vfs_inode_dotl.c | 3 +++
 2 files changed, 6 insertions(+)

--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -469,6 +469,9 @@ 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;
 }
 
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -105,6 +105,9 @@ 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;
 }