From: Imre Deak <imre.deak@intel.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: horia.geanta@nxp.com, linux-kernel@vger.kernel.org,
linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v4 1/4] lib/scatterlist: Fix mapping iterator when sg->offset is greater than PAGE_SIZE
Date: Mon, 24 Jun 2019 20:35:33 +0300 [thread overview]
Message-ID: <20190624173533.GA809@ideak-desk.fi.intel.com> (raw)
In-Reply-To: <20190620060221.q4pbsqzsza3pxs42@gondor.apana.org.au>
Hi,
On Thu, Jun 20, 2019 at 02:02:21PM +0800, Herbert Xu wrote:
> On Mon, Jun 17, 2019 at 09:15:02PM +0000, Christophe Leroy wrote:
> > All mapping iterator logic is based on the assumption that sg->offset
> > is always lower than PAGE_SIZE.
> >
> > But there are situations where sg->offset is such that the SG item
> > is on the second page.
could you explain how sg->offset becomes >= PAGE_SIZE?
--Imre
> > In that case sg_copy_to_buffer() fails
> > properly copying the data into the buffer. One of the reason is
> > that the data will be outside the kmapped area used to access that
> > data.
> >
> > This patch fixes the issue by adjusting the mapping iterator
> > offset and pgoffset fields such that offset is always lower than
> > PAGE_SIZE.
> >
> > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> > Fixes: 4225fc8555a9 ("lib/scatterlist: use page iterator in the mapping iterator")
> > Cc: stable@vger.kernel.org
> > ---
> > lib/scatterlist.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
>
> Good catch.
>
> > @@ -686,7 +686,12 @@ static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
> > sg = miter->piter.sg;
> > pgoffset = miter->piter.sg_pgoffset;
> >
> > - miter->__offset = pgoffset ? 0 : sg->offset;
> > + offset = pgoffset ? 0 : sg->offset;
> > + while (offset >= PAGE_SIZE) {
> > + miter->piter.sg_pgoffset = ++pgoffset;
> > + offset -= PAGE_SIZE;
> > + }
>
> How about
>
> miter->piter.sg_pgoffset += offset >> PAGE_SHIFT;
> offset &= PAGE_SIZE - 1;
>
> Thanks,
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2019-06-24 22:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-17 21:15 [PATCH v4 0/4] Additional fixes on Talitos driver Christophe Leroy
2019-06-17 21:15 ` [PATCH v4 1/4] lib/scatterlist: Fix mapping iterator when sg->offset is greater than PAGE_SIZE Christophe Leroy
2019-06-20 6:02 ` Herbert Xu
2019-06-24 17:35 ` Imre Deak [this message]
2019-06-25 1:20 ` Herbert Xu
2019-06-17 21:15 ` [PATCH v4 2/4] crypto: talitos - move struct talitos_edesc into talitos.h Christophe Leroy
2019-06-17 21:15 ` [PATCH v4 3/4] crypto: talitos - fix hash on SEC1 Christophe Leroy
2019-06-17 21:15 ` [PATCH v4 4/4] crypto: talitos - drop icv_ool Christophe Leroy
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