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

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Message-ID: <1c0e94ff-617b-4672-addb-8933f92edc29@lunn.ch>
Date:   Sat, 14 Oct 2023 18:31:16 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Jiawen Wu <jiawenwu@...stnetic.com>,
        Mengyuan Lou <mengyuanlou@...-swift.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] net: txgbe: replace deprecated strncpy with strscpy

On Thu, Oct 12, 2023 at 09:20:04PM +0000, 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.
> 
> Based on usage part_str usage within txgbe_read_pba_string(), we expect
> part_str to be NUL-terminated but not necessarily NUL-padded:
> |       /* put a null character on the end of our string */
> |       pba_num[10] = '\0';
> 
> Interestingly, part_str is not used after txgbe_read_pba_string():
> | ...
> |	err = txgbe_read_pba_string(wx, part_str, TXGBE_PBANUM_LENGTH);
> |	if (err)
> |		strscpy(part_str, "Unknown", sizeof(part_str));
> |
> |	netif_info(wx, probe, netdev, "%pM\n", netdev->dev_addr);
> |
> |	return 0;
> |
> |err_remove_phy:
> |	txgbe_remove_phy(txgbe);
> |err_release_hw:
> |	wx_clear_interrupt_scheme(wx);
> |	wx_control_hw(wx, false);
> |err_free_mac_table:
> |	kfree(wx->mac_table);
> |err_pci_release_regions:
> |	pci_release_selected_regions(pdev,
> |				     pci_select_bars(pdev, IORESOURCE_MEM));
> |err_pci_disable_dev:
> |	pci_disable_device(pdev);
> |	return err;
> |}
> ... this means this strncpy (or now strscpy) is probably useless. For
> now, let's make the swap to strscpy() as I am not sure if this is truly
> dead code or not.

Hi Julian

I agree, this looks like dead code.

Jiawen, please could you submit a patch cleaning this up. Either swap
to strscpy() and make use of the string, or delete it all.


    Andrew

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