linux-hardening - [PATCH 5.15 341/484] power: supply: bq24190_charger: replace deprecated strncpy with strscpy

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Message-ID: <20240815131954.589989595@linuxfoundation.org>
Date: Thu, 15 Aug 2024 15:23:19 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: stable@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	patches@...ts.linux.dev,
	linux-hardening@...r.kernel.org,
	Justin Stitt <justinstitt@...gle.com>,
	Kees Cook <keescook@...omium.org>,
	Sebastian Reichel <sebastian.reichel@...labora.com>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 341/484] power: supply: bq24190_charger: replace deprecated strncpy with strscpy

5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Justin Stitt <justinstitt@...gle.com>

[ Upstream commit b0009b8bed98bd5d59449af48781703df261c247 ]

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 bdi->model_name to be NUL-terminated based on its usage with
sysfs_emit and format strings:

val->strval is assigned to bdi->model_name in
bq24190_charger_get_property():
1186 | val->strval = bdi->model_name;

... then in power_supply_sysfs.c we use value.strval with a format string:
311  | ret = sysfs_emit(buf, "%s\n", value.strval);

we assigned value.strval via:
285  | ret = power_supply_get_property(psy, psp, &value);
... which invokes psy->desc->get_property():
1210 | return psy->desc->get_property(psy, psp, val);

with bq24190_charger_get_property():
1320 | static const struct power_supply_desc bq24190_charger_desc = {
...
1325 | 	.get_property		= bq24190_charger_get_property,

Moreover, no NUL-padding is required as bdi is zero-allocated in
bq24190_charger.c:
1798 | bdi = devm_kzalloc(dev, sizeof(*bdi), 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.

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>
Reviewed-by: Kees Cook <keescook@...omium.org>
Link: https://lore.kernel.org/r/20231020-strncpy-drivers-power-supply-bq24190_charger-c-v1-1-e896223cb795@google.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/power/supply/bq24190_charger.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/supply/bq24190_charger.c b/drivers/power/supply/bq24190_charger.c
index 90ac5e59a5d6f..8a4729ee1ab19 100644
--- a/drivers/power/supply/bq24190_charger.c
+++ b/drivers/power/supply/bq24190_charger.c
@@ -1727,7 +1727,7 @@ static int bq24190_probe(struct i2c_client *client,
 
 	bdi->client = client;
 	bdi->dev = dev;
-	strncpy(bdi->model_name, id->name, I2C_NAME_SIZE);
+	strscpy(bdi->model_name, id->name, sizeof(bdi->model_name));
 	mutex_init(&bdi->f_reg_lock);
 	bdi->f_reg = 0;
 	bdi->ss_reg = BQ24190_REG_SS_VBUS_STAT_MASK; /* impossible state */
-- 
2.43.0