linux-hardening - [PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

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Message-ID: <20231023-strncpy-drivers-scsi-bnx2fc-bnx2fc_fcoe-c-v1-1-a3736943cde2@google.com>
Date: Mon, 23 Oct 2023 20:12:22 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Saurav Kashyap <skashyap@...vell.com>, Javed Hasan <jhasan@...vell.com>, 
	GR-QLogic-Storage-Upstream@...vell.com, 
	"James E.J. Bottomley" <jejb@...ux.ibm.com>, "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-hardening@...r.kernel.org, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] scsi: bnx2fc: 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 hba->chip_num to be NUL-terminated based on its usage with
format strings:

	snprintf(fc_host_symbolic_name(lport->host), 256,
		 "%s (QLogic %s) v%s over %s",
		BNX2FC_NAME, hba->chip_num, BNX2FC_VERSION,
		interface->netdev->name);

Moreover, NUL-padding is not required as hba is zero-allocated from its
callsite:

	hba = kzalloc(sizeof(*hba), GFP_KERNEL);

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.

Regarding stats_addr->version, I've opted to also use strscpy() instead
of strscpy_pad() as I typically see these XYZ_get_strings() pass
zero-allocated data. I couldn't track all of where
bnx2fc_ulp_get_stats() is used and if required, we could opt for
strscpy_pad().

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>
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
 drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index 05ddbb9bb7d8..3ebfb09329ad 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -1737,32 +1737,32 @@ static int bnx2fc_bind_pcidev(struct bnx2fc_hba *hba)
 
 	switch (pdev->device) {
 	case PCI_DEVICE_ID_NX2_57710:
-		strncpy(hba->chip_num, "BCM57710", BCM_CHIP_LEN);
+		strscpy(hba->chip_num, "BCM57710", sizeof(hba->chip_num));
 		break;
 	case PCI_DEVICE_ID_NX2_57711:
-		strncpy(hba->chip_num, "BCM57711", BCM_CHIP_LEN);
+		strscpy(hba->chip_num, "BCM57711", sizeof(hba->chip_num));
 		break;
 	case PCI_DEVICE_ID_NX2_57712:
 	case PCI_DEVICE_ID_NX2_57712_MF:
 	case PCI_DEVICE_ID_NX2_57712_VF:
-		strncpy(hba->chip_num, "BCM57712", BCM_CHIP_LEN);
+		strscpy(hba->chip_num, "BCM57712", sizeof(hba->chip_num));
 		break;
 	case PCI_DEVICE_ID_NX2_57800:
 	case PCI_DEVICE_ID_NX2_57800_MF:
 	case PCI_DEVICE_ID_NX2_57800_VF:
-		strncpy(hba->chip_num, "BCM57800", BCM_CHIP_LEN);
+		strscpy(hba->chip_num, "BCM57800", sizeof(hba->chip_num));
 		break;
 	case PCI_DEVICE_ID_NX2_57810:
 	case PCI_DEVICE_ID_NX2_57810_MF:
 	case PCI_DEVICE_ID_NX2_57810_VF:
-		strncpy(hba->chip_num, "BCM57810", BCM_CHIP_LEN);
+		strscpy(hba->chip_num, "BCM57810", sizeof(hba->chip_num));
 		break;
 	case PCI_DEVICE_ID_NX2_57840:
 	case PCI_DEVICE_ID_NX2_57840_MF:
 	case PCI_DEVICE_ID_NX2_57840_VF:
 	case PCI_DEVICE_ID_NX2_57840_2_20:
 	case PCI_DEVICE_ID_NX2_57840_4_10:
-		strncpy(hba->chip_num, "BCM57840", BCM_CHIP_LEN);
+		strscpy(hba->chip_num, "BCM57840", sizeof(hba->chip_num));
 		break;
 	default:
 		pr_err(PFX "Unknown device id 0x%x\n", pdev->device);
@@ -1800,7 +1800,7 @@ static int bnx2fc_ulp_get_stats(void *handle)
 	if (!stats_addr)
 		return -EINVAL;
 
-	strncpy(stats_addr->version, BNX2FC_VERSION,
+	strscpy(stats_addr->version, BNX2FC_VERSION,
 		sizeof(stats_addr->version));
 	stats_addr->txq_size = BNX2FC_SQ_WQES_MAX;
 	stats_addr->rxq_size = BNX2FC_CQ_WQES_MAX;

---
base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c
change-id: 20231023-strncpy-drivers-scsi-bnx2fc-bnx2fc_fcoe-c-f24335846e35

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