linux-kernel - Re: [PATCH] mtd: nand: Fix memory allocation in nanddev_bbt

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Date:   Tue, 27 Nov 2018 09:22:32 +0100
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Schrempf Frieder <frieder.schrempf@...tron.de>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mtd: nand: Fix memory allocation in nanddev_bbt_init()

On Tue, 27 Nov 2018 07:44:52 +0000
Schrempf Frieder <frieder.schrempf@...tron.de> wrote:

> Fix the size of the buffer allocated to store the in-memory BBT.
> This bug was previously hidden by a different bug, that was fixed in
> d098093ba06e.

Oops :-/.

> 
> Fixes: 9c3736a3de21 ("mtd: nand: Add core infrastructure to deal with NAND devices")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> ---
>  drivers/mtd/nand/bbt.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/bbt.c b/drivers/mtd/nand/bbt.c
> index 56cde38..c12497f 100644
> --- a/drivers/mtd/nand/bbt.c
> +++ b/drivers/mtd/nand/bbt.c
> @@ -27,7 +27,8 @@ int nanddev_bbt_init(struct nand_device *nand)
>  	unsigned int nwords = DIV_ROUND_UP(nblocks * bits_per_block,
>  					   BITS_PER_LONG);
>  
> -	nand->bbt.cache = kzalloc(nwords, GFP_KERNEL);
> +	nand->bbt.cache = kzalloc(nwords * (BITS_PER_LONG / BITS_PER_BYTE),

I prefer

					 * sizeof(*nand->bbt.cache)
If you're okay with this change, I'll fix it when applying (no need to
send a new version).

Thanks,

Boris

> +				  GFP_KERNEL);
>  	if (!nand->bbt.cache)
>  		return -ENOMEM;
>