linux-hardening - [PATCH] accel/habanalabs: refactor deprecated strncpy to strscpy

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Date:   Fri, 25 Aug 2023 22:09:51 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Oded Gabbay <ogabbay@...nel.org>, Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        linux-hardening@...r.kernel.org,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] accel/habanalabs: refactor deprecated strncpy to strscpy_pad

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We see that `prop->cpucp_info.card_name` is supposed to be
NUL-terminated based on its usage within `__hwmon_device_register()`
(wherein it's called "name"):
|	if (name && (!strlen(name) || strpbrk(name, "-* \t\n")))
|		dev_warn(dev,
|			 "hwmon: '%s' is not a valid name attribute, please fix\n",
|			 name);

A suitable replacement is `strscpy_pad` [2] due to the fact that it
guarantees both NUL-termination and NUL-padding on its destination
buffer.

NUL-padding on `prop->cpucp_info.card_name` is not strictly necessary as
`hdev->prop` is explicitly zero-initialized but should be used
regardless as it gets copied out to userspace directly -- as per Kees' suggestion.

Link: 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>
Suggested-by: Kees Cook <keescook@...omium.org>
---
Note: build-tested only

This patch combines three previous strncpy refactor patches into one.
1) https://lore.kernel.org/all/20230824-strncpy-drivers-accel-habanalabs-gaudi-gaudi-c-v1-1-a7fb9054734c@google.com/
2) https://lore.kernel.org/all/20230824-strncpy-drivers-accel-habanalabs-gaudi2-gaudi2-c-v1-1-1a37b65576b4@google.com/
3) https://lore.kernel.org/all/20230824-strncpy-drivers-accel-habanalabs-goya-goya-c-v1-1-b81d5639e7a3@google.com/
---
 drivers/accel/habanalabs/gaudi/gaudi.c   | 4 ++--
 drivers/accel/habanalabs/gaudi2/gaudi2.c | 4 ++--
 drivers/accel/habanalabs/goya/goya.c     | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/accel/habanalabs/gaudi/gaudi.c b/drivers/accel/habanalabs/gaudi/gaudi.c
index 056e2ef44afb..1b5fe4d0cf5d 100644
--- a/drivers/accel/habanalabs/gaudi/gaudi.c
+++ b/drivers/accel/habanalabs/gaudi/gaudi.c
@@ -660,7 +660,7 @@ static int gaudi_set_fixed_properties(struct hl_device *hdev)
 	prop->pcie_dbi_base_address = mmPCIE_DBI_BASE;
 	prop->pcie_aux_dbi_reg_addr = CFG_BASE + mmPCIE_AUX_DBI;
 
-	strncpy(prop->cpucp_info.card_name, GAUDI_DEFAULT_CARD_NAME,
+	strscpy_pad(prop->cpucp_info.card_name, GAUDI_DEFAULT_CARD_NAME,
 					CARD_NAME_MAX_LEN);
 
 	prop->max_pending_cs = GAUDI_MAX_PENDING_CS;
@@ -8000,7 +8000,7 @@ static int gaudi_cpucp_info_get(struct hl_device *hdev)
 		return rc;
 
 	if (!strlen(prop->cpucp_info.card_name))
-		strncpy(prop->cpucp_info.card_name, GAUDI_DEFAULT_CARD_NAME,
+		strscpy_pad(prop->cpucp_info.card_name, GAUDI_DEFAULT_CARD_NAME,
 				CARD_NAME_MAX_LEN);
 
 	hdev->card_type = le32_to_cpu(hdev->asic_prop.cpucp_info.card_type);
diff --git a/drivers/accel/habanalabs/gaudi2/gaudi2.c b/drivers/accel/habanalabs/gaudi2/gaudi2.c
index 20c4583f12b0..2ba7a50103bc 100644
--- a/drivers/accel/habanalabs/gaudi2/gaudi2.c
+++ b/drivers/accel/habanalabs/gaudi2/gaudi2.c
@@ -2431,7 +2431,7 @@ static int gaudi2_set_fixed_properties(struct hl_device *hdev)
 	prop->pcie_dbi_base_address = CFG_BASE + mmPCIE_DBI_BASE;
 	prop->pcie_aux_dbi_reg_addr = CFG_BASE + mmPCIE_AUX_DBI;
 
-	strncpy(prop->cpucp_info.card_name, GAUDI2_DEFAULT_CARD_NAME, CARD_NAME_MAX_LEN);
+	strscpy_pad(prop->cpucp_info.card_name, GAUDI2_DEFAULT_CARD_NAME, CARD_NAME_MAX_LEN);
 
 	prop->mme_master_slave_mode = 1;
 
@@ -2884,7 +2884,7 @@ static int gaudi2_cpucp_info_get(struct hl_device *hdev)
 	}
 
 	if (!strlen(prop->cpucp_info.card_name))
-		strncpy(prop->cpucp_info.card_name, GAUDI2_DEFAULT_CARD_NAME, CARD_NAME_MAX_LEN);
+		strscpy_pad(prop->cpucp_info.card_name, GAUDI2_DEFAULT_CARD_NAME, CARD_NAME_MAX_LEN);
 
 	/* Overwrite binning masks with the actual binning values from F/W */
 	hdev->dram_binning = prop->cpucp_info.dram_binning_mask;
diff --git a/drivers/accel/habanalabs/goya/goya.c b/drivers/accel/habanalabs/goya/goya.c
index 7c685e6075f6..024ccf2e159b 100644
--- a/drivers/accel/habanalabs/goya/goya.c
+++ b/drivers/accel/habanalabs/goya/goya.c
@@ -466,7 +466,7 @@ int goya_set_fixed_properties(struct hl_device *hdev)
 	prop->pcie_dbi_base_address = mmPCIE_DBI_BASE;
 	prop->pcie_aux_dbi_reg_addr = CFG_BASE + mmPCIE_AUX_DBI;
 
-	strncpy(prop->cpucp_info.card_name, GOYA_DEFAULT_CARD_NAME,
+	strscpy_pad(prop->cpucp_info.card_name, GOYA_DEFAULT_CARD_NAME,
 		CARD_NAME_MAX_LEN);
 
 	prop->max_pending_cs = GOYA_MAX_PENDING_CS;
@@ -5122,7 +5122,7 @@ int goya_cpucp_info_get(struct hl_device *hdev)
 	}
 
 	if (!strlen(prop->cpucp_info.card_name))
-		strncpy(prop->cpucp_info.card_name, GOYA_DEFAULT_CARD_NAME,
+		strscpy_pad(prop->cpucp_info.card_name, GOYA_DEFAULT_CARD_NAME,
 				CARD_NAME_MAX_LEN);
 
 	return 0;

---
base-commit: 706a741595047797872e669b3101429ab8d378ef
change-id: 20230825-strncpy-habanalabs-combined-c43b1d11960e

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