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b=H4sIAJnXC2UC/53NQQ6CMBCF4auYrh0DbRHqynsYQ7AM0ERaMiVFQ ri7hZUudfne4vsX5pEMenY5LIwwGG+cjUMcD0x3lW0RTB034wkXiUol+JGsHmaoyQQkD93UOwu VHkw5uAmp7HFEAg1aNbwukkw8sGGRGwgb89pTt3vcnfGjo3kvh3R7/4iEFFJQScZVLnPVYHFtn WufeNKuZ1sl8E9Z/SDzKBdCFlLw+iwl/5LXdX0D8+S7ATsBAAA= X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1695274906; l=2206; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=KXXNR06fDm8CjylUce2un2Htp6ByU6W92dU8RA1crQ0=; b=tRLI7Wgpm3CdsY5jEJd3FjvprLZLD8Phcapc19BeFcZk7gq7oTTv/7ibAxYIwzP3dYb+qpKyy lrJy6DcBeL0CVRcBMo3/zxp4L1fKyeXVokEzzyyqcYvL35mdA/5lfZC X-Mailer: b4 0.12.3 Message-ID: <20230921-strncpy-drivers-hwmon-acpi_power_meter-c-v3-1-307552c6ec3f@google.com> Subject: [PATCH v3] hwmon: refactor deprecated strncpy From: Justin Stitt To: Jean Delvare , Guenter Roeck Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Justin Stitt X-Spam-Status: No, score=-7.5 required=5.0 tests=DATE_IN_PAST_12_24, 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]); Thu, 21 Sep 2023 14:07:13 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1777683677262909594 X-GMAIL-MSGID: 1777683677262909594 `strncpy` is deprecated for use on NUL-terminated destination strings [1]. Let's refactor this kcalloc() + strncpy() into a kmemdup_nul() which has more obvious behavior and is less error prone. To avoid truncating the last byte supply `...length + 1` to kmemdup_nul() as `element->string.length` does not account for the trailing null as made obvious from it's definition (and associated comment): | u32 length; /* # of bytes in string, excluding trailing null */ ... this is precisely what the original kcalloc invocation did as well. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt --- Changes in v3: - refactor to use kmemdup_nul() (thanks Thomas and Kees) - change commit msg to reflect ^ - rebase onto 2cf0f71562387282 - Link to v2: https://lore.kernel.org/r/20230919-strncpy-drivers-hwmon-acpi_power_meter-c-v2-1-8348432d6442@google.com Changes in v2: - use memcpy over strscpy (thanks Kees) - Link to v1: https://lore.kernel.org/r/20230914-strncpy-drivers-hwmon-acpi_power_meter-c-v1-1-905297479fe8@google.com --- drivers/hwmon/acpi_power_meter.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- base-commit: 2cf0f715623872823a72e451243bbf555d10d032 change-id: 20230914-strncpy-drivers-hwmon-acpi_power_meter-c-c9f2d8053bef Best regards, -- Justin Stitt diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_power_meter.c index fa28d447f0df..146c4f09c897 100644 --- a/drivers/hwmon/acpi_power_meter.c +++ b/drivers/hwmon/acpi_power_meter.c @@ -796,14 +796,13 @@ static int read_capabilities(struct acpi_power_meter_resource *resource) goto error; } - *str = kcalloc(element->string.length + 1, sizeof(u8), - GFP_KERNEL); + *str = kmemdup_nul(element->string.pointer, element->string.length + 1, + GFP_KERNEL); if (!*str) { res = -ENOMEM; goto error; } - strncpy(*str, element->string.pointer, element->string.length); str++; }