| Message ID | 20231020-strncpy-drivers-power-supply-bq24190_charger-c-v1-1-e896223cb795@google.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | power: supply: bq24190_charger: replace deprecated strncpy with strscpy | expand |
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: linux-hardening@vger.kernel.org > Signed-off-by: Justin Stitt <justinstitt@google.com> > --- > 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 <keescook@chromium.org>
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,
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;
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@vger.kernel.org Signed-off-by: Justin Stitt <justinstitt@google.com> --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/power/supply/bq24190_charger.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: bb55d7f7f7445abcc8db50e6a65d4315e79f75c7 change-id: 20231020-strncpy-drivers-power-supply-bq24190_charger-c-6bcc105fc23b Best regards, -- Justin Stitt <justinstitt@google.com>