linux-kernel - Re: [v2 PATCH] lib/mpi: Fix buffer overrun when SG is too long

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Message-ID: <Y6VJzBcN3LvY5j60@gondor.apana.org.au>
Date:   Fri, 23 Dec 2022 14:25:16 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     Roberto Sassu <roberto.sassu@...weicloud.com>, dhowells@...hat.com,
        davem@...emloft.net, zohar@...ux.ibm.com,
        dmitry.kasatkin@...il.com, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Tadeusz Struk <tadeusz.struk@...el.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [v2 PATCH] lib/mpi: Fix buffer overrun when SG is too long

On Wed, Dec 21, 2022 at 12:53:29PM -0800, Eric Biggers wrote:
>
> That's fine, I guess.  One quirk of the above approach is that if the last
> needed element of the scatterlist has a lot of extra pages, this will iterate
> through all those extra pages, processing 0 bytes from each.  It could just stop
> when done.  I suppose it's not worth worrying about that case, though.

Ideally this should be handled in the sg_miter interface, IOW,
it should allow us to cap the SG list at a certain number of bytes
as opposed to a certain number of entries.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt