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

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Date: Tue, 10 Oct 2023 14:20:28 -0700
From: Jesse Brandeburg <jesse.brandeburg@...el.com>
To: Justin Stitt <justinstitt@...gle.com>, 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>
CC: <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 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

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.

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

Thanks,
Jesse