netdev - Re: [PATCH net-next 0/7] net: intel: replace deprecated strncpy uses

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Date: Tue, 10 Oct 2023 16:22:44 -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>, 
	linux-hardening@...r.kernel.org, intel-wired-lan@...ts.osuosl.org, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 0/7] net: intel: replace deprecated strncpy uses

On Tue, Oct 10, 2023 at 4:19 PM Jesse Brandeburg
<jesse.brandeburg@...el.com> wrote:
>
> On 10/10/2023 3:26 PM, Justin Stitt wrote:
> > Hi,
> >
> > This series aims to eliminate uses of strncpy() as it is a deprecated
> > interface [1] with many viable replacements available.
> >
> > Predominantly, strscpy() is the go-to replacement as it guarantees
> > NUL-termination on the destination buffer (which strncpy does not). With
> > that being said, I did not identify any buffer overread problems as the
> > size arguments were carefully measured to leave room for trailing
> > NUL-bytes. Nonetheless, we should favor more robust and less ambiguous
> > interfaces.
> >
> > Previously, each of these patches was sent individually at:
> > 1) https://lore.kernel.org/all/20231009-strncpy-drivers-net-ethernet-intel-e100-c-v1-1-ca0ff96868a3@google.com/
> > 2) https://lore.kernel.org/all/20231010-strncpy-drivers-net-ethernet-intel-e1000-e1000_main-c-v1-1-b1d64581f983@google.com/
> > 3) https://lore.kernel.org/all/20231010-strncpy-drivers-net-ethernet-intel-fm10k-fm10k_ethtool-c-v1-1-dbdc4570c5a6@google.com/
> > 4) https://lore.kernel.org/all/20231010-strncpy-drivers-net-ethernet-intel-i40e-i40e_ddp-c-v1-1-f01a23394eab@google.com/
> > 5) https://lore.kernel.org/all/20231010-strncpy-drivers-net-ethernet-intel-igb-igb_main-c-v1-1-d796234a8abf@google.com/
> > 6) https://lore.kernel.org/all/20231010-strncpy-drivers-net-ethernet-intel-igbvf-netdev-c-v1-1-69ccfb2c2aa5@google.com/
> > 7) https://lore.kernel.org/all/20231010-strncpy-drivers-net-ethernet-intel-igc-igc_main-c-v1-1-f1f507ecc476@google.com/
> >
> > Consider these dead as this series is their new home :)
> >
> > I found all these instances with: $ rg "strncpy\("
> >
> > This series may collide in a not-so-nice way with [3]. This series can
> > go in after that one with a rebase. I'll send a v2 if necessary.
> >
> > [3]: https://lore.kernel.org/netdev/20231003183603.3887546-1-jesse.brandeburg@intel.com/
> >
> > 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
> > Signed-off-by: Justin Stitt <justinstitt@...gle.com>
>
> Thanks Justin for fixing all these!
>
> For the series:
> Reviewed-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
>
> PS: have you considered adding a script to scripts/coccinelle/api which
> might catch and try to fix future (ab)users of strncpy?

There is a checkpatch routine for it. Also, the docs are littered with
aversions to strncpy. With that being said, I would not be opposed
to adding more checks, though.

Once I'm more caught up on all the outstanding strncpy uses,
I'll look into adding some coccinelle support.

>

Thanks
Justin