linux-kernel - Re: [PATCH] PPC: in celleb_show_cpuinfo() convert strncpy(x, y, sizeof(x)) to strlcpy

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Date:	Thu, 6 Mar 2008 16:44:24 +0100
From:	Segher Boessenkool <segher@...nel.crashing.org>
To:	Roel Kluin <12o3l@...cali.nl>
Cc:	paulus@...ba.org, arnd@...db.de, linuxppc-dev@...abs.org,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PPC: in celleb_show_cpuinfo() convert strncpy(x, y, sizeof(x)) to strlcpy 

> This patch was not yet tested. Please confirm it's right.
> ---
> strncpy does not append '\0' if the length of the source string equals
> the size parameter, strlcpy does.

strlcpy() doesn't fill the rest of the array with zeroes, strncpy()
does.  This could matter (information leak, for example), although
I doubt it does here.

> -	strncpy(celleb_machine_type, ptr, sizeof(celleb_machine_type));
> +	strlcpy(celleb_machine_type, ptr, sizeof(celleb_machine_type));
>  	celleb_machine_type[sizeof(celleb_machine_type)-1] = 0;

That last statement makes the strncpy() case always zero-terminated,
so this patch isn't necessary.  Oh, and neither the old nor the new
code handles the case where the string doesn't fit (other than just
cutting it short); is that the wanted behaviour?

Segher

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