linux-hardening - Re: [PATCH] igc: replace deprecated strncpy with strscpy

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Message-ID: <CAFhGd8qE1oO0q91Y7sEq342qH1ty+KSMGUkczaQAJgghPBBX0w@mail.gmail.com>
Date: Tue, 10 Oct 2023 14:43:21 -0700
From: Justin Stitt <justinstitt@...gle.com>
To: Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] igc: replace deprecated strncpy with strscpy

On Tue, Oct 10, 2023 at 2:22 PM Jesse Brandeburg
<jesse.brandeburg@...el.com> wrote:
>
> On 10/10/2023 2:15 PM, Justin Stitt wrote:
> > `strncpy` is deprecated for use on NUL-terminated destination strings
> > [1] and as such we should prefer more robust and less ambiguous string
> > interfaces.
> >
> > We expect netdev->name to be NUL-terminated based on its use with format
> > strings:
> > |       if (q_vector->rx.ring && q_vector->tx.ring)
> > |               sprintf(q_vector->name, "%s-TxRx-%u", netdev->name,
> >
> > Furthermore, we do not need NUL-padding as netdev is already
> > zero-allocated:
> > |       netdev = alloc_etherdev_mq(sizeof(struct igc_adapter),
> > |                                  IGC_MAX_TX_QUEUES);
> > ...
> > alloc_etherdev() -> alloc_etherdev_mq() -> alloc_etherdev_mqs() ->
> > alloc_netdev_mqs() ...
> > |       p = kvzalloc(alloc_size, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
> >
> > Considering the above, a suitable replacement is `strscpy` [2] due to
> > the fact that it guarantees NUL-termination on the destination buffer
> > without unnecessarily NUL-padding.
> >
> > Let's also opt for the more idiomatic strscpy usage of (dest, src,
> > sizeof(dest)) instead of (dest, src, SOME_LEN).
> >
>
>
> Please see my comments on the igbvf patch.

Ah, I sent too many before checking back in. I see
your comments now. Responded over there!

>
>
Thanks
Justin