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: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested only.
Found with: $ rg "strncpy\("
---
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 3f99cb9590ba..1db290ee2591 100644
--- 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;
---
base-commit: bb55d7f7f7445abcc8db50e6a65d4315e79f75c7
change-id: 20231020-strncpy-drivers-power-supply-bq24190_charger-c-6bcc105fc23b
Best regards,
--
Justin Stitt <[email protected]>
On Fri, Oct 20, 2023 at 06:14:47PM +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 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: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested only.
>
> Found with: $ rg "strncpy\("
> ---
> 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 3f99cb9590ba..1db290ee2591 100644
> --- 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));
struct bq24190_dev_info {
...
char model_name[I2C_NAME_SIZE];
Length replacement looks correct.
struct i2c_device_id {
char name[I2C_NAME_SIZE];
And it looks like this wasn't accidentally leaving strings unterminated,
so that's nice.
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On Fri, 20 Oct 2023 18:14:47 +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 bdi->model_name to be NUL-terminated based on its usage with
> sysfs_emit and format strings:
>
> [...]
Applied, thanks!
[1/1] power: supply: bq24190_charger: replace deprecated strncpy with strscpy
commit: b0009b8bed98bd5d59449af48781703df261c247
Best regards,
--
Sebastian Reichel <[email protected]>