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b=H4sIAJ9LMGUC/53NTQ6DIBCG4asY1p1GsP6kq96jcYE41UkUzEBQY 7x7qUfo8v0W33MIj0zoxTM7BGMkT86mULdMmFHbAYH61ELlqpC5rMEHtmbZoWeKyB4sBliJcUL vIRCsk2y2DWZNFgwUZaVzVatOdw+RPhfGD22X925Tj+SD4/3io/yt/0pRggTsy0IpNE1eNa/Bu WHCu3GzaM/z/AKAqSjd6wAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1697663905; l=2897; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=lMVpXzAbthcxiCNfxcyNDG6TNfyPkqxWUDDeMmHC4Uw=; b=x86eQLBjWQhfaxdwh4ogz4PqhKCrv1sPzCQUF/5jtKH/6gtucs0svlqppMZ0fYjPZlWMlUBvW JKrY4BC107aBjmBPeGu+f1S+rMK+/2wLcsr58oG3dm4WiQ2tbTgNxRy X-Mailer: b4 0.12.3 Message-ID: <20231018-strncpy-drivers-net-wireless-ti-wl18xx-main-c-v2-1-ab828a491ce5@google.com> Subject: [PATCH v2] wifi: wl18xx: replace deprecated strncpy with strscpy From: Justin Stitt To: Kalle Valo Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Justin Stitt X-Spam-Status: No, score=-8.4 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on fry.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (fry.vger.email [0.0.0.0]); Wed, 18 Oct 2023 14:18:53 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780129660317889895 X-GMAIL-MSGID: 1780129660317889895 strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. wl->chip.phy_fw_ver_str is obviously intended to be NUL-terminated by the deliberate comment telling us as much. Furthermore, its only use is drivers/net/wireless/ti/wlcore/debugfs.c shows us it should be NUL-terminated since its used in scnprintf: 492 | DRIVER_STATE_PRINT_STR(chip.phy_fw_ver_str); which is defined as: | #define DRIVER_STATE_PRINT_STR(x) DRIVER_STATE_PRINT(x, "%s") ... | #define DRIVER_STATE_PRINT(x, fmt) \ | (res += scnprintf(buf + res, DRIVER_STATE_BUF_LEN - res,\ | #x " = " fmt "\n", wl->x)) We can also see that NUL-padding is not required. 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. The very fact that a plain-english comment had to be made alongside a manual NUL-byte assignment for such a simple purpose shows why strncpy is faulty. It has non-obvious behavior that has to be clarified every time it is used (and if it isn't then the reader suffers). 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@vger.kernel.org Signed-off-by: Justin Stitt Reviewed-by: Kees Cook --- Changes in v2: - add wifi: to subject (thanks Jeff) - Link to v1: https://lore.kernel.org/r/20231017-strncpy-drivers-net-wireless-ti-wl18xx-main-c-v1-1-ed5322ec8068@google.com --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/net/wireless/ti/wl18xx/main.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) --- base-commit: 58720809f52779dc0f08e53e54b014209d13eebb change-id: 20231017-strncpy-drivers-net-wireless-ti-wl18xx-main-c-356a0272bab4 Best regards, -- Justin Stitt diff --git a/drivers/net/wireless/ti/wl18xx/main.c b/drivers/net/wireless/ti/wl18xx/main.c index 0b3cf8477c6c..1e4a430d1543 100644 --- a/drivers/net/wireless/ti/wl18xx/main.c +++ b/drivers/net/wireless/ti/wl18xx/main.c @@ -1516,12 +1516,9 @@ static int wl18xx_handle_static_data(struct wl1271 *wl, struct wl18xx_static_data_priv *static_data_priv = (struct wl18xx_static_data_priv *) static_data->priv; - strncpy(wl->chip.phy_fw_ver_str, static_data_priv->phy_version, + strscpy(wl->chip.phy_fw_ver_str, static_data_priv->phy_version, sizeof(wl->chip.phy_fw_ver_str)); - /* make sure the string is NULL-terminated */ - wl->chip.phy_fw_ver_str[sizeof(wl->chip.phy_fw_ver_str) - 1] = '\0'; - wl1271_info("PHY firmware version: %s", static_data_priv->phy_version); return 0;