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Thu, 27 Jul 2023 15:26:52 -0700 (PDT) Date: Thu, 27 Jul 2023 22:26:41 +0000 Mime-Version: 1.0 X-B4-Tracking: v=1; b=H4sIACDvwmQC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyDHUUlJIzE vPSU3UzU4B8JSMDI2MDcyNz3eL80rwUIJmsm1aco2uSlmxqamaZYm5umKoE1FNQlJqWWQE2Lzq 2thYAMKv4Nl8AAAA= X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1690496811; l=2165; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=xEnu5xQr3cyZZvwQfMubiCiEuFBVC3Uk0Y9589JdUxw=; b=hmOqBlRYlYKaC3Yr5Zy8g3r9+9++L/pbK5ub/HORCIbyUCI0NGjnrADamWXFeaNB3CVKyg4I+ L5n1tag1LikDFx+k0EHDanF323xxdNABjjW0T5SEFnG7vM0e2joX6sH X-Mailer: b4 0.12.3 Message-ID: <20230727-sound-soc-fsl-v1-1-4fc0ed7e0366@google.com> Subject: [PATCH] ASoC: fsl_micfil: refactor deprecated strncpy From: Justin Stitt To: Shengjiu Wang , Xiubo Li , Fabio Estevam , Nicolin Chen , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai Cc: alsa-devel@alsa-project.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Kees Cook , Justin Stitt Message-ID-Hash: PHZJIKKDA6EHXJWRCDJJOFZUZAT5TNE4 X-Message-ID-Hash: PHZJIKKDA6EHXJWRCDJJOFZUZAT5TNE4 X-MailFrom: 3LO_CZAsKCkMozxynsxynyylttlqj.htrfqxf-ij0jqfqxf-uwtojhy.twl@flex--justinstitt.bounces.google.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: `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_ always the case for `strncpy`! In this case, though, there was great care taken to ensure that the destination buffer would be NUL-terminated through the use of `len - 1` ensuring that the previously zero-initialized buffer would not overwrite the last NUL byte. This means that there's no bug here. However, `strscpy` will add a mandatory NUL byte to the destination buffer as promised by the following `strscpy` implementation [3]: | /* Hit buffer length without finding a NUL; force NUL-termination. */ | if (res) | dest[res-1] = '\0'; This means we can lose the `- 1` which clears up whats happening here. All the while, we get one step closer to eliminating the ambiguous `strncpy` api in favor of its less ambiguous replacement like `strscpy`, `strscpy_pad`, `strtomem` and `strtomem_pad` amongst others. [1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [2]: manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [3]: https://elixir.bootlin.com/linux/v6.3/source/lib/string.c#L183 Link: https://github.com/KSPP/linux/issues/90 Signed-off-by: Justin Stitt --- sound/soc/fsl/fsl_micfil.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: 57012c57536f8814dec92e74197ee96c3498d24e change-id: 20230727-sound-soc-fsl-4fc5569d771e Best regards, -- Justin Stitt diff --git a/sound/soc/fsl/fsl_micfil.c b/sound/soc/fsl/fsl_micfil.c index 3f08082a55be..fe28b27e50d0 100644 --- a/sound/soc/fsl/fsl_micfil.c +++ b/sound/soc/fsl/fsl_micfil.c @@ -1044,7 +1044,7 @@ static int fsl_micfil_probe(struct platform_device *pdev) return -ENOMEM; micfil->pdev = pdev; - strncpy(micfil->name, np->name, sizeof(micfil->name) - 1); + strscpy(micfil->name, np->name, sizeof(micfil->name)); micfil->soc = of_device_get_match_data(&pdev->dev);