# Re: \[PATCH 1/2\] kernfs\_path\_from\_node\_locked: don't overwrite nlen

- From: Tejun Heo \<hidden\>
- Date: 2016-05-02 16:33:14 
- List: cgroups
- Page: https://ratatoskr.run/cgroups/2016/05/4743535
- Thread: https://ratatoskr.run/linux-api/2016/04/4731916/t.md

```text
On Wed, Apr 20, 2016 at 03:43:13PM -0400, Tejun Heo wrote:
> On Sun, Apr 17, 2016 at 03:04:31PM -0500, serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org wrote:
> > From: Serge Hallyn <redacted>
> > 
> > We've calculated @len to be the bytes we need for '/..' entries from
> > @kn_from to the common ancestor, and calculated @nlen to be the extra
> > bytes we need to get from the common ancestor to @kn_to.  We use them
> > as such at the end.  But in the loop copying the actual entries, we
> > overwrite @nlen.  Use a temporary variable for that instead.
> > 
> > Without this, the return length, when the buffer is large enough, is
> > wrong.  (When the buffer is NULL or too small, the returned value is
> > correct. The buffer contents are also correct.)
> > 
> > Interestingly, no callers of this function are affected by this as of
> > yet.  However the upcoming cgroup_show_path() will be.
> > 
> > Signed-off-by: Serge Hallyn <redacted>
> 
> Acked-by: Tejun Heo <redacted>
> 
> Greg, can you please pick this one up for v4.6?

Looks like Greg missed this one.  Greg, I'll route this through
cgroup/for-4.6-fixes.

Thanks.

-- 
tejun
```