linux-kernel - Re: [PATCH v2 13/16] block: sed-opal: check size of shadow mbr

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Message-ID: <20190119172902.GA14875@hacktheplanet>
Date:   Sat, 19 Jan 2019 12:29:02 -0500
From:   Scott Bauer <sbauer@...donthack.me>
To:     David Kozub <zub@...ux.fjfi.cvut.cz>
Cc:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        hch@...radead.org, jonathan.derrick@...el.com
Subject: Re: [PATCH v2 13/16] block: sed-opal: check size of shadow mbr

On Thu, Jan 17, 2019 at 09:31:53PM +0000, David Kozub wrote:
> From: Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>
> 
> Check whether the shadow mbr does fit in the provided space on the
> target. Also a proper firmware should handle this case and return an
> error we may prevent problems or even damage with crappy firmwares.
> +	len = response_get_u64(&dev->parsed, 4);
> +	if (shadow->offset + shadow->size > len) {
> +		pr_debug("MBR: does not fit in shadow (%llu vs. %llu)\n",
> +			 shadow->offset + shadow->size, len);
> +		return -ENOSPC;
> +	}

Can we please change this check to the following:

if (shadow->size > len || shadow->offset > len - shadow->size)

Thanks

> -- 
> 2.20.1
> 
>