linux-kernel - Re: [PATCH 1/2] kernfs_path_from_node

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Message-ID: <20160420194313.GA4775@htj.duckdns.org>
Date:	Wed, 20 Apr 2016 15:43:13 -0400
From:	Tejun Heo <tj@...nel.org>
To:	serge.hallyn@...ntu.com
Cc:	linux-kernel@...r.kernel.org, adityakali@...gle.com,
	linux-api@...r.kernel.org, containers@...ts.linux-foundation.org,
	cgroups@...r.kernel.org, akpm@...ux-foundation.org,
	ebiederm@...ssion.com, gregkh@...uxfoundation.org,
	lizefan@...wei.com, hannes@...xchg.org
Subject: Re: [PATCH 1/2] kernfs_path_from_node_locked: don't overwrite nlen

On Sun, Apr 17, 2016 at 03:04:31PM -0500, serge.hallyn@...ntu.com wrote:
> From: Serge Hallyn <serge.hallyn@...ntu.com>
> 
> 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 <serge.hallyn@...ntu.com>

Acked-by: Tejun Heo <tj@...nel.org>

Greg, can you please pick this one up for v4.6?

Thanks.

-- 
tejun