[PATCH driver-core-next] kernfs: fix hash calculation in kernfs_rename_ns()

[PATCH driver-core-next] kernfs: fix hash calculation in kernfs_rename_ns()

[Tejun Heo]

3eef34ad7dc3 ("kernfs: implement kernfs_get_parent(),
kernfs_name/path() and friends") restructured kernfs_rename_ns() such
that new name assignment happens under kernfs_rename_lock;
unfortunately, it mistakenly passed NULL to kernfs_name_hash() to
calculate the new hash if the name hasn't changed, which can lead to
oops.

Fix it by using kn->name and kn->ns when calculating the new hash.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Dan Carpenter dan.carpenter@oracle.com
---
 fs/kernfs/dir.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 939684e..ba8c858 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1296,7 +1296,7 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
 
 	spin_unlock_irq(&kernfs_rename_lock);
 
-	kn->hash = kernfs_name_hash(new_name, new_ns);
+	kn->hash = kernfs_name_hash(kn->name, kn->ns);
 	kernfs_link_sibling(kn);
 
 	kernfs_put(old_parent);

Re: [PATCH driver-core-next] kernfs: fix hash calculation in kernfs_rename_ns()

[Greg Kroah-Hartman]

On Mon, Feb 10, 2014 at 05:57:09PM -0500, Tejun Heo wrote:
> 3eef34ad7dc3 ("kernfs: implement kernfs_get_parent(),
> kernfs_name/path() and friends") restructured kernfs_rename_ns() such
> that new name assignment happens under kernfs_rename_lock;
> unfortunately, it mistakenly passed NULL to kernfs_name_hash() to
> calculate the new hash if the name hasn't changed, which can lead to
> oops.
> 
> Fix it by using kn->name and kn->ns when calculating the new hash.

Now applied, thanks.

Also, can you look into the merge of 3.14-rc2 into the driver-core-next
branch?  There are some conflicts in the kernfs code due to the lockdep
changes that I couldn't easily verify I got right, so I didn't do the
merge.  Could you give me a diff of the merge for me to work off of?

thanks,

greg k-h

Re: [PATCH driver-core-next] kernfs: fix hash calculation in kernfs_rename_ns()

[Tejun Heo]

Hello, Greg.

On Mon, Feb 10, 2014 at 04:01:41PM -0800, Greg Kroah-Hartman wrote:
> Also, can you look into the merge of 3.14-rc2 into the driver-core-next
> branch?  There are some conflicts in the kernfs code due to the lockdep
> changes that I couldn't easily verify I got right, so I didn't do the
> merge.  Could you give me a diff of the merge for me to work off of?

Sure thing.  It can be resolved by simply ignoring the
driver-core-linus side.  kernfs_drain() updates in driver-core-next
already has all the necessary lockdep flag checks through
kernfs_lockdep().

The following git branch contains a test merge between
driver-core-next and rc2.

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git driver-core-next-test-merge-rc2

Thanks!

-- 
tejun

Re: [PATCH driver-core-next] kernfs: fix hash calculation in kernfs_rename_ns()

[Greg Kroah-Hartman]

On Mon, Feb 10, 2014 at 07:39:56PM -0500, Tejun Heo wrote:
> Hello, Greg.
> 
> On Mon, Feb 10, 2014 at 04:01:41PM -0800, Greg Kroah-Hartman wrote:
> > Also, can you look into the merge of 3.14-rc2 into the driver-core-next
> > branch?  There are some conflicts in the kernfs code due to the lockdep
> > changes that I couldn't easily verify I got right, so I didn't do the
> > merge.  Could you give me a diff of the merge for me to work off of?
> 
> Sure thing.  It can be resolved by simply ignoring the
> driver-core-linus side.  kernfs_drain() updates in driver-core-next
> already has all the necessary lockdep flag checks through
> kernfs_lockdep().
> 
> The following git branch contains a test merge between
> driver-core-next and rc2.
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git driver-core-next-test-merge-rc2

Thanks, I took this merge and pulled it into my tree.

greg k-h