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From: PanBian <bianpan2016@163.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Subject: Re: [Xen-devel] [PATCH] pvcalls-front: fixes incorrect error handling
Date: Tue, 27 Nov 2018 08:58:23 +0800	[thread overview]
Message-ID: <20181127005823.GB125510@bp> (raw)
In-Reply-To: <1f765e81-ed89-d110-74b1-cc8029a4555f@oracle.com>

On Mon, Nov 26, 2018 at 03:31:39PM -0500, Boris Ostrovsky wrote:
> On 11/21/18 9:07 PM, Pan Bian wrote:
> > kfree() is incorrectly used to release the pages allocated by
> > __get_free_page() and __get_free_pages(). Use the matching deallocators
> > i.e., free_page() and free_pages(), respectively.
> >
> > Signed-off-by: Pan Bian <bianpan2016@163.com>
> > ---
> >  drivers/xen/pvcalls-front.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
> > index 2f11ca7..77224d8 100644
> > --- a/drivers/xen/pvcalls-front.c
> > +++ b/drivers/xen/pvcalls-front.c
> > @@ -385,8 +385,8 @@ static int create_active(struct sock_mapping *map, int *evtchn)
> >  out_error:
> >  	if (*evtchn >= 0)
> >  		xenbus_free_evtchn(pvcalls_front_dev, *evtchn);
> > -	kfree(map->active.data.in);
> > -	kfree(map->active.ring);
> > +	free_pages((unsigned long)map->active.data.in, PVCALLS_RING_ORDER);
> 
> Is map->active.data.in guaranteed to be NULL when entering this routine?

I am not sure yet. Sorry for that. I observed the mismatches between
__get_free_page and kfree, and submitted the patch.

But I think your consideration is reasonable. A better solution is to
directly free bytes, a local variable that holds __get_free_pages return
value. If you agree, I will rewrite the patch.

Thanks,
Pan

> 
> -boris
> 
> > +	free_page((unsigned long)map->active.ring);
> >  	return ret;
> >  }
> >  
> 


  reply	other threads:[~2018-11-27  0:58 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-22  2:07 Pan Bian
2018-11-26 20:31 ` [Xen-devel] " Boris Ostrovsky
2018-11-27  0:58   ` PanBian [this message]
2018-11-27 20:37     ` Stefano Stabellini
2018-11-27 20:57       ` Boris Ostrovsky
2018-11-27 21:08         ` Stefano Stabellini
2018-11-27 22:47           ` Boris Ostrovsky
2018-11-27 22:51             ` Stefano Stabellini
2018-11-29 16:54 ` Juergen Gross

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