[PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

[PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

[Justin Stitt]

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@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.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@google.com>

Re: [PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

[Kees Cook]

On Mon, Oct 23, 2023 at 08:12:22PM +0000, Justin Stitt wrote:
> 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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

This all looks correct to me.

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

[Martin K. Petersen]

Justin,

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

Applied to 6.8/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH] scsi: bnx2fc: replace deprecated strncpy with strscpy

[Martin K. Petersen]

On Mon, 23 Oct 2023 20:12:22 +0000, Justin Stitt wrote:

> 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:
> 
> [...]

Applied to 6.8/scsi-queue, thanks!

[1/1] scsi: bnx2fc: replace deprecated strncpy with strscpy
      https://git.kernel.org/mkp/scsi/c/b04a2eff9e9c

-- 
Martin K. Petersen	Oracle Linux Engineering