This is a note to let you know that I've just added the patch titled
cifs: Do not lookup hashed negative dentry in cifs_atomic_open
to the 3.6-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:
cifs-do-not-lookup-hashed-negative-dentry-in-cifs_atomic_open.patch
and it can be found in the queue-3.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 3798f47aa276b332c30da499cb4df4577e2f8872 Mon Sep 17 00:00:00 2001
From: Sachin Prabhu <[email protected]>
Date: Mon, 5 Nov 2012 11:39:32 +0000
Subject: cifs: Do not lookup hashed negative dentry in cifs_atomic_open
From: Sachin Prabhu <[email protected]>
commit 3798f47aa276b332c30da499cb4df4577e2f8872 upstream.
We do not need to lookup a hashed negative directory since we have
already revalidated it before and have found it to be fine.
This also prevents a crash in cifs_lookup() when it attempts to rehash
the already hashed negative lookup dentry.
The patch has been tested using the reproducer at
https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28
Reported-by: Vit Zahradka <[email protected]>
Signed-off-by: Sachin Prabhu <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/cifs/dir.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -392,7 +392,16 @@ cifs_atomic_open(struct inode *inode, st
* in network traffic in the other paths.
*/
if (!(oflags & O_CREAT)) {
- struct dentry *res = cifs_lookup(inode, direntry, 0);
+ struct dentry *res;
+
+ /*
+ * Check for hashed negative dentry. We have already revalidated
+ * the dentry and it is fine. No need to perform another lookup.
+ */
+ if (!d_unhashed(direntry))
+ return -ENOENT;
+
+ res = cifs_lookup(inode, direntry, 0);
if (IS_ERR(res))
return PTR_ERR(res);
Patches currently in stable-queue which might be from [email protected] are
queue-3.6/cifs-do-not-lookup-hashed-negative-dentry-in-cifs_atomic_open.patch
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