[PATCH] ALSA: hda/tegra: refactor deprecated strncpy

[PATCH] ALSA: hda/tegra: refactor deprecated strncpy

[Justin Stitt]

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on its destination buffer argument which is
_not_ the case for `strncpy`!

It should be noted that the current implementation is unlikely to have a
bug because `drv_name` is a string literal with a size of 9 while
`card->driver` has a size of 16. However, it is probably worthwhile to
switch to a more robust and less ambiguous interface.

[1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
[2]: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html

Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
 sound/pci/hda/hda_tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/pci/hda/hda_tegra.c b/sound/pci/hda/hda_tegra.c
index 9d0ab043880b..f16740500d46 100644
--- a/sound/pci/hda/hda_tegra.c
+++ b/sound/pci/hda/hda_tegra.c
@@ -378,14 +378,14 @@ static int hda_tegra_first_init(struct azx *chip, struct platform_device *pdev)
 	}
 
 	/* driver name */
-	strncpy(card->driver, drv_name, sizeof(card->driver));
+	strscpy(card->driver, drv_name, sizeof(card->driver));
 	/* shortname for card */
 	sname = of_get_property(np, "nvidia,model", NULL);
 	if (!sname)
 		sname = drv_name;
 	if (strlen(sname) > sizeof(card->shortname))
 		dev_info(card->dev, "truncating shortname for card\n");
-	strncpy(card->shortname, sname, sizeof(card->shortname));
+	strscpy(card->shortname, sname, sizeof(card->shortname));
 
 	/* longname for card */
 	snprintf(card->longname, sizeof(card->longname),

---
base-commit: c1a515d3c0270628df8ae5f5118ba859b85464a2
change-id: 20230803-sound-pci-hda-c3a712b72a35

Best regards,
--
Justin Stitt <justinstitt@google.com>

Re: [PATCH] ALSA: hda/tegra: refactor deprecated strncpy

[Takashi Iwai]

On Mon, 07 Aug 2023 19:49:28 +0200,
Justin Stitt wrote:
> 
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on its destination buffer argument which is
> _not_ the case for `strncpy`!
> 
> It should be noted that the current implementation is unlikely to have a
> bug because `drv_name` is a string literal with a size of 9 while
> `card->driver` has a size of 16. However, it is probably worthwhile to
> switch to a more robust and less ambiguous interface.
> 
> [1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> [2]: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
> 
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Thanks, applied.


Takashi