Re: [PATCH] proc: check vma->vm_file before dereferencing

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 16 Oct 2012 01:52:30 +0400
Cyrill Gorcunov <gorcunov@openvz.org> wrote:

> On Mon, Oct 15, 2012 at 02:40:48PM -0700, Andrew Morton wrote:
> > On Mon, 15 Oct 2012 19:30:03 +0400
> > Stanislav Kinsbursky <skinsbursky@parallels.com> wrote:
> > 
> > > It can be equal to NULL.
> > > 
> > 
> > Please write better changelogs, so people do not have to ask questions
> > such as:
> > 
> > - Under what conditions does this bug trigger?
> > 
> > - In which kernel version(s)?
> > 
> > - Is it a post-3.6 regression?
> 
> Andrew, would the following changelog be enough?
> 
> The commit 7b540d0646ce122f0ba4520412be91e530719742 switched
> proc_map_files_readdir to use @f_mode directly instead of grabbing
> @file reference, but same time the test for @vm_file presence was
> lost leading to nil dereference. The patch brings the test back.
> 
> The all proc_map_files feature is CONFIG_CHECKPOINT_RESTORE wrapped
> (which is set to 'n' by default) so the bug doesn't affect regular
> kernels.
> 
> The regression is 3.7-rc1 only as far as I can tell.

Ah, I see, great, thanks.