linux-kernel - [PATCH v2] qlcnic: replace deprecated strncpy with strscpy

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Message-ID: <20231207-strncpy-drivers-net-ethernet-qlogic-qlcnic-qlcnic_83xx_init-c-v2-1-eb1a20a91b2a@google.com>
Date:   Thu, 07 Dec 2023 21:42:22 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Shahed Shaikh <shshaikh@...vell.com>,
        Manish Chopra <manishc@...vell.com>,
        GR-Linux-NIC-Dev@...vell.com,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH v2] qlcnic: replace deprecated strncpy with strscpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We expect fw_info->fw_file_name to be NUL-terminated based on its use
within _request_firmware_prepare() wherein `name` refers to it:
|       if (firmware_request_builtin_buf(firmware, name, dbuf, size)) {
|               dev_dbg(device, "using built-in %s\n", name);
|               return 0; /* assigned */
|       }
... and with firmware_request_builtin() also via `name`:
|       if (strcmp(name, b_fw->name) == 0) {

There is no evidence that NUL-padding is required.

Additionally replace size macro (QLC_FW_FILE_NAME_LEN) with
sizeof(fw_info->fw_file_name) to more directly tie the maximum buffer
size to the destination buffer:

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.

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@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Changes in v2:
- update commit msg with sizeof() rationale (thanks Kees)
- rebase onto mainline bee0e7762ad2c602
- Link to v1: https://lore.kernel.org/r/20231012-strncpy-drivers-net-ethernet-qlogic-qlcnic-qlcnic_83xx_init-c-v1-1-f0008d5e43be@google.com
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
 drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
index c95d56e56c59..b733374b4dc5 100644
--- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
+++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
@@ -2092,8 +2092,8 @@ static int qlcnic_83xx_run_post(struct qlcnic_adapter *adapter)
 		return -EINVAL;
 	}
 
-	strncpy(fw_info->fw_file_name, QLC_83XX_POST_FW_FILE_NAME,
-		QLC_FW_FILE_NAME_LEN);
+	strscpy(fw_info->fw_file_name, QLC_83XX_POST_FW_FILE_NAME,
+		sizeof(fw_info->fw_file_name));
 
 	ret = request_firmware(&fw_info->fw, fw_info->fw_file_name, dev);
 	if (ret) {
@@ -2396,12 +2396,12 @@ static int qlcnic_83xx_get_fw_info(struct qlcnic_adapter *adapter)
 		switch (pdev->device) {
 		case PCI_DEVICE_ID_QLOGIC_QLE834X:
 		case PCI_DEVICE_ID_QLOGIC_QLE8830:
-			strncpy(fw_info->fw_file_name, QLC_83XX_FW_FILE_NAME,
-				QLC_FW_FILE_NAME_LEN);
+			strscpy(fw_info->fw_file_name, QLC_83XX_FW_FILE_NAME,
+				sizeof(fw_info->fw_file_name));
 			break;
 		case PCI_DEVICE_ID_QLOGIC_QLE844X:
-			strncpy(fw_info->fw_file_name, QLC_84XX_FW_FILE_NAME,
-				QLC_FW_FILE_NAME_LEN);
+			strscpy(fw_info->fw_file_name, QLC_84XX_FW_FILE_NAME,
+				sizeof(fw_info->fw_file_name));
 			break;
 		default:
 			dev_err(&pdev->dev, "%s: Invalid device id\n",

---
base-commit: bee0e7762ad2c6025b9f5245c040fcc36ef2bde8
change-id: 20231012-strncpy-drivers-net-ethernet-qlogic-qlcnic-qlcnic_83xx_init-c-7858019dc583

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