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Date:   Thu, 17 Nov 2022 15:11:41 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Denis Arefev <arefev@swemel.ru>
Cc:     Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
        lvc-project@linuxtesting.org, trufanov@swemel.ru, vfh@swemel.ru
Subject: Re: [PATCH] mtd: lpddr: Added literal suffix
Message-ID: <20221117151141.20cfc362@xps-13>
In-Reply-To: <20221117123625.117161-1-arefev@swemel.ru>
References: <20221117123625.117161-1-arefev@swemel.ru>
Organization: Bootlin
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Hi Denis,

arefev@swemel.ru wrote on Thu, 17 Nov 2022 15:36:25 +0300:

> The value of an arithmetic expression
> 1 << lpddr->qinfo->DevSizeShift is subject to overflow
> due to a failure to cast operands to a larger data
> type before perfoming arithmetic
>=20
> Signed-off-by: Denis Arefev <arefev@swemel.ru>
> ---
>  drivers/mtd/lpddr/lpddr_cmds.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/mtd/lpddr/lpddr_cmds.c b/drivers/mtd/lpddr/lpddr_cmd=
s.c
> index ee063baed136..360b2af8340b 100644
> --- a/drivers/mtd/lpddr/lpddr_cmds.c
> +++ b/drivers/mtd/lpddr/lpddr_cmds.c
> @@ -61,7 +61,7 @@ struct mtd_info *lpddr_cmdset(struct map_info *map)
>  		mtd->_point =3D lpddr_point;
>  		mtd->_unpoint =3D lpddr_unpoint;
>  	}
> -	mtd->size =3D 1 << lpddr->qinfo->DevSizeShift;
> +	mtd->size =3D 1UL << lpddr->qinfo->DevSizeShift;

Are you sure it should not be 1ULL instead? otherwise I don't see how
the overflow can happen?

>  	mtd->erasesize =3D 1 << lpddr->qinfo->UniformBlockSizeShift;
>  	mtd->writesize =3D 1 << lpddr->qinfo->BufSizeShift;
> =20


Thanks,
Miqu=C3=A8l