From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
kernel-team@lge.com, stable@vger.kernel.org
Subject: Re: [PATCH 1/3] zram: fix operator precedence to get offset
Date: Mon, 17 Apr 2017 10:21:05 +0900 [thread overview]
Message-ID: <20170417012105.GA518@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20170414153251.GA16910@bgram>
Hello,
On (04/15/17 00:33), Minchan Kim wrote:
> On Fri, Apr 14, 2017 at 02:07:47PM +0900, Sergey Senozhatsky wrote:
> > On (04/13/17 09:17), Minchan Kim wrote:
> > [..]
> > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > > index 9e2199060040..83c38a123242 100644
> > > --- a/drivers/block/zram/zram_drv.c
> > > +++ b/drivers/block/zram/zram_drv.c
> > > @@ -930,7 +930,7 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
> > > }
> > >
> > > index = sector >> SECTORS_PER_PAGE_SHIFT;
> > > - offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT;
> > > + offset = (sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
> >
> > sorry, can it actually produce different results?
>
> I got your point. Actually, offset was wrong but rw_page is called
> with PAGE_SIZE io while that offset is related to only partial io
> (non-PAGEE size io). IOW, although the wrong offset it is never used
> in functions.
>
> To find subtle corruption in ppc64, I added some debug code to
> catch up wrong buffer overflow and found it with other bugs but
> didn't prove the specific case is valid case or not. Good catch, Sergey!
>
> However, it should be *fixed* to prevent confusion in future but surely,
> no need to go to the stable. I will send reply to Greg to prevent merging
> it to *stable* when he send review asking to merge.
cool. thanks!
> And next week I will send another fix which *maybe* removes code to get the
> offset in zram_rw_page.
sounds interesting!
-ss
next prev parent reply other threads:[~2017-04-17 1:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 0:17 [PATCH 1/3] zram: fix operator precedence to get offset Minchan Kim
2017-04-13 0:17 ` [PATCH 2/3] zram: do not use copy_page with non-page alinged address Minchan Kim
2017-04-14 5:41 ` Sergey Senozhatsky
2017-04-14 15:40 ` Minchan Kim
2017-04-17 1:48 ` Sergey Senozhatsky
2017-04-13 0:17 ` [PATCH 3/3] zsmalloc: expand class bit Minchan Kim
2017-04-14 5:07 ` [PATCH 1/3] zram: fix operator precedence to get offset Sergey Senozhatsky
2017-04-14 15:33 ` Minchan Kim
2017-04-17 1:21 ` Sergey Senozhatsky [this message]
2017-04-17 1:54 ` Sergey Senozhatsky
2017-04-17 2:14 ` Minchan Kim
2017-04-17 10:50 ` Sergey Senozhatsky
2017-04-17 10:53 ` Sergey Senozhatsky
2017-04-17 23:53 ` Minchan Kim
2017-04-18 1:53 ` Sergey Senozhatsky
2017-04-18 2:47 ` Minchan Kim
2017-04-17 1:21 ` Sergey Senozhatsky
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