power: supply: bq256xx: 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 bq->model_name to be NUL-terminated based on its usage with
sysfs_emit and format strings:
val->strval is assigned to bq->model_name in
bq256xx_get_charger_property():
| val->strval = bq->model_name;
... then in power_supply_sysfs.c we use value.strval with a format string:
| ret = sysfs_emit(buf, "%s\n", value.strval);
we assigned value.strval via:
| ret = power_supply_get_property(psy, psp, &value);
... which invokes psy->desc->get_property():
| return psy->desc->get_property(psy, psp, val);
with bq256xx_get_charger_property():
| static const struct power_supply_desc bq256xx_power_supply_desc = {
...
| .get_property = bq256xx_get_charger_property,
Moreover, no NUL-padding is required as bq is zero-allocated in
bq256xx_charger.c:
| bq = devm_kzalloc(dev, sizeof(*bq), 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.
Let's also opt to use the more idiomatic strscpy() usage of (dest, src,
sizeof(dest)) as this more closely ties the destination buffer and the
length.
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
Similar-to: https://lore.kernel.org/all/20231020-strncpy-drivers-power-supply-bq24190_charger-c-v1-1-e896223cb795@google.com/
Similar-to: https://lore.kernel.org/all/20231020-strncpy-drivers-power-supply-bq2515x_charger-c-v1-1-46664c6edf78@google.com/
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-bq256xx_charger-c-v1-1-2fad856124f9@google.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
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