netdev - Re: [patch] isdn: strcpy() => strlcpy()

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Message-ID: <20101005164306.GP19804@ZenIV.linux.org.uk>
Date:	Tue, 5 Oct 2010 17:43:06 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Dan Carpenter <error27@...il.com>
Cc:	Karsten Keil <isdn@...ux-pingi.de>, netdev@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch] isdn: strcpy() => strlcpy()

On Tue, Oct 05, 2010 at 06:34:48PM +0200, Dan Carpenter wrote:
> setup.phone and setup.eazmsn are 32 character buffers.
> rcvmsg.msg_data.byte_array is a 48 character buffer.
> sc_adapter[card]->channel[rcvmsg.phy_link_no - 1].dn is 50 chars.
> 
> I changed the strcpy() so strlcpy() because that's safest.

ITYM "I papered it over, so potentially broken behaviour is harder to
find now"...

> -				strcpy(setup.phone,&(rcvmsg.msg_data.byte_array[4]));
> -				strcpy(setup.eazmsn,
> -					sc_adapter[card]->channel[rcvmsg.phy_link_no-1].dn);
> +				strlcpy(setup.phone, &(rcvmsg.msg_data.byte_array[4]),
> +					sizeof(setup.phone));

OK, so what should be done if the damn array contents _is_ longer than that?

> +				strlcpy(setup.eazmsn,
> +					sc_adapter[card]->channel[rcvmsg.phy_link_no - 1].dn,
> +					sizeof(setup.eazmsn));

Ditto.

> -			strcpy(sc_adapter[card]->channel[rcvmsg.phy_link_no-1].dn,rcvmsg.msg_data.byte_array);
> +			strlcpy(sc_adapter[card]->channel[rcvmsg.phy_link_no - 1].dn,
> +				rcvmsg.msg_data.byte_array,
> +				sizeof(rcvmsg.msg_data.byte_array));

Huh?  Is it or is it not NUL-terminated?  If it is, then change is pure
cargo-culting; if it is not, you are asking for nasal daemons to fly.
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