linux-kernel - Re: [dm-devel] [PATCH v3 01/26] block: Fix a buffer overrun in bio_integrity

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Date:	Tue, 2 Oct 2012 10:08:47 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Kent Overstreet <koverstreet@...gle.com>
Cc:	linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
	dm-devel@...hat.com, axboe@...nel.dk,
	"Martin K. Petersen" <martin.petersen@...cle.com>, tj@...nel.org
Subject: Re: [dm-devel] [PATCH v3 01/26] block: Fix a buffer overrun in
 bio_integrity_split()

On Mon, Oct 01, 2012 at 02:42:41PM -0700, Kent Overstreet wrote:

[..]
> Here's the new patch:
> 
> 
> commit e270c9ca843b5c86d59431b0d7a676b7846946d6
> Author: Kent Overstreet <koverstreet@...gle.com>
> Date:   Mon Oct 1 14:41:08 2012 -0700
> 
>     block: Fix a buffer overrun in bio_integrity_split()
>     
>     bio_integrity_split() seemed to be confusing pointers and arrays -
>     bip_vec in bio_integrity_payload is an array appended to the end of the
>     payload, so the bio_vecs in struct bio_pair need to come immediately
>     after the bio_integrity_payload they're for, and there was an assignment
>     in bio_integrity_split() that didn't make any sense.
>     
>     Also, changed bio_integrity_split() to not refer to the bvecs embedded
>     in struct bio_pair, in case there's padding between them and
>     bip->bip_vec.
>     
>     Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
>     CC: Jens Axboe <axboe@...nel.dk>
>     CC: Martin K. Petersen <martin.petersen@...cle.com>
> 
> diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
> index a3f28f3..4ae22a8 100644
> --- a/fs/bio-integrity.c
> +++ b/fs/bio-integrity.c
> @@ -694,15 +694,12 @@ void bio_integrity_split(struct bio *bio, struct bio_pair *bp, int sectors)
>  	bp->bio1.bi_integrity = &bp->bip1;
>  	bp->bio2.bi_integrity = &bp->bip2;
>  
> -	bp->iv1 = bip->bip_vec[0];
> -	bp->iv2 = bip->bip_vec[0];
> +	*bp->bip1.bip_vec = bip->bip_vec[0];
> +	*bp->bip2.bip_vec = bip->bip_vec[0];

I think this is horrible. Why not introduce bvec pointer in bip (like bio),
to cover the case when bvec are not inline.

Thanks
Vivek
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