linux-kernel - Re: [PATCH 2/4] Add MMC Password Protection (lock/unlock) support V8: mmc_key

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Message-ID: <20061213155531.1kpbmi3pk40kkoos@webmail.kernalert.de>
Date:	Wed, 13 Dec 2006 15:55:31 +0100
From:	Frank Seidel <frank@...nalert.de>
To:	Anderson Briglia <anderson.briglia@...t.org.br>
Cc:	Russell King <rmk+lkml@....linux.org.uk>,
	"Lizardo Anderson (EXT-INdT/Manaus)" <anderson.lizardo@...t.org.br>,
	Pierre Ossman <drzeus-list@...eus.cx>,
	linux-kernel@...r.kernel.org,
	"Aguiar Carlos (EXT-INdT/Manaus)" <carlos.aguiar@...t.org.br>,
	Tony Lindgren <tony@...mide.com>,
	ext David Brownell <david-b@...bell.net>
Subject: Re: [PATCH 2/4] Add MMC Password Protection (lock/unlock) support
	V8: mmc_key_retention.diff

Quoting Anderson Briglia <anderson.briglia@...t.org.br>:
> [...]
Hi,
thats really cool stuff you're providing with your patches. :)
I have some feedback or questions some parts here.
But as i just started trying to get into kernelhacking you probably
better don't take my notes to serious, please.

> Index: linux-linus-2.6/drivers/mmc/mmc_sysfs.c
> ===================================================================
> --- linux-linus-2.6.orig/drivers/mmc/mmc_sysfs.c        2006-12-04 [...]
> +static int mmc_key_instantiate(struct key *key, const void *data,   
> size_t datalen)
> +{
> +        struct mmc_key_payload *mpayload, *zap;
> +        int ret;
> +
> +        zap = NULL;
What is zap here for? future use?
And wouldn't it be good to also initialize mplayload here?

> +        ret = -EINVAL;
Is there a special reason why you already assign the errors to the
return value variable before its clear that the assignment is needed?


> +        if (datalen <= 0 || datalen > MMC_KEYLEN_MAXBYTES || !data) {
Isn't the last "|| !data" redundant as you already tested if datalen ==0?

> +                pr_debug("Invalid data\n");
> +                goto error;
> +        }
> +
> +        ret = key_payload_reserve(key, datalen);
> +        if (ret < 0) {
> +                pr_debug("ret = %d\n", ret);
> +                goto error;
> +        }
> +
> +        ret = -ENOMEM;
Same as above: Why do you in any case want to assign it here?

> +        mpayload = kmalloc(sizeof(*mpayload) + datalen, GFP_KERNEL);
I may be totally wrong, but is dereferencing a not initialized pointer
(even just for using sizeof) really ok? Wouldn't it be safer to use
a sizeof(struct mmc_key_payload) here?

Thanks,
Frank


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