power: supply: bq24190_charger: 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 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
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.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@collabora.com>

diff --git a/drivers/power/supply/bq24190_charger.c b/drivers/power/supply/bq24190_charger.c
index 3f99cb9590ba2bef0105551eb661755647e4e5aa..1db290ee2591adef9e89437eec0dde519e958675 100644 (file)
--- a/drivers/power/supply/bq24190_charger.c
+++ b/drivers/power/supply/bq24190_charger.c
@@ -1803,7 +1803,7 @@ 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->charge_type = POWER_SUPPLY_CHARGE_TYPE_FAST;
        bdi->f_reg = 0;