linux-kernel - NAK: [PATCH][mtd-next] mtd: sharpslpart: fix overflow on block

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Date:   Wed, 8 Nov 2017 15:57:57 +0000
From:   Colin Ian King <colin.king@...onical.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        Andrea Adami <andrea.adami@...il.com>,
        linux-mtd@...ts.infradead.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: NAK: [PATCH][mtd-next] mtd: sharpslpart: fix overflow on block_adr
 calculation

On 08/11/17 15:46, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> Multiplying block_num and mtd->erasesize may potentially overflow
> as they are both unsigned ints and so the multiplication is evaluated
> in unsigned int arithmetic .  Cast block_adr to off_t to ensure
> multiplication is off_t sized to avoid any potential overflow.
> 
> Detected by CoverityScan, CID#1461264 ("Unintentional integer overflow")
> 
> Fixes: fff1e32a50c0 ("mtd: sharpslpart: Add sharpslpart partition parser")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/mtd/parsers/sharpslpart.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/parsers/sharpslpart.c b/drivers/mtd/parsers/sharpslpart.c
> index 5fe0079ea5ed..b1d97aa3bac4 100644
> --- a/drivers/mtd/parsers/sharpslpart.c
> +++ b/drivers/mtd/parsers/sharpslpart.c
> @@ -244,7 +244,7 @@ static int sharpsl_nand_read_laddr(struct mtd_info *mtd,
>  		return -EINVAL;
>  
>  	block_num = ftl->log2phy[log_num];
> -	block_adr = block_num * mtd->erasesize;
> +	block_adr = (loff_t)block_num * mtd->erasesize;
>  	block_ofs = mtd_mod_by_eb((u32)from, mtd);
>  
>  	err = mtd_read(mtd, block_adr + block_ofs, len, &retlen, buf);
> 

Sorry, ignore this, there is another place that does this that needs
some attention. I'll sent V2 shortly.