linux-kernel - Re: [PATCH] igbvf: replace deprecated strncpy with strscpy

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Message-ID: <CAFhGd8ppobxMnvrMT4HrRkf0LvHE1P-utErp8Tk22Fb9OO=8Rw@mail.gmail.com>
Date:   Tue, 10 Oct 2023 14:41:10 -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] igbvf: replace deprecated strncpy with strscpy

On Tue, Oct 10, 2023 at 2:20 PM Jesse Brandeburg
<jesse.brandeburg@...el.com> wrote:
>
> On 10/10/2023 2:12 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 usage with
> > `strlen` and format strings:
> > |       if (strlen(netdev->name) < (IFNAMSIZ - 5)) {
> > |               sprintf(adapter->tx_ring->name, "%s-tx-0", netdev->name);
> >
> > Moreover, we do not need NUL-padding as netdev is already
> > zero-allocated:
> > |       netdev = alloc_etherdev(sizeof(struct igbvf_adapter));
> > ...
> > 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.
> >
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> > Link: https://github.com/KSPP/linux/issues/90
> > Cc: linux-hardening@...r.kernel.org
> > Signed-off-by: Justin Stitt <justinstitt@...gle.com>
> > ---
>
> Thanks Justin for these patches, please make sure you mark the subject
> line as per the netdev rules:
> [PATCH net-next v1] etc etc

Sure, I'll resend!

>
> I'd also prefer they came in as part of one series with a good cover
> letter, at the very least for the Intel drivers, and you probably could
> combine any others (netdev) together up to the 15 patch limit.

Got it :)

>
> Please mention how you found these issues, via automated tool or via
> coccinelle script, manual grepping, etc?

rg "strncpy\(" > pain.txt

>
> Thanks,
> Jesse
>