| Message ID | 20230921-strncpy-drivers-i3c-master-c-v1-1-9fdb8d8169e1@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | i3c: replace deprecated strncpy | expand |
On Thu, Sep 21, 2023 at 03:51:04AM +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > We should prefer more robust and less ambiguous string interfaces. > > We expect adap->name to be NUL-terminated based on i2c_adapter name use: > | dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name); > > NUL-padding does not seem to be required as `master` is zero-allocated > and `i3c_master_to_i2c_adapter` simply returns a field from within > `master`: > | master = devm_kzalloc(dev, sizeof(*master), GFP_KERNEL); > ... > | struct i2c_adapter *adap = i3c_master_to_i2c_adapter(master); > ... > | static struct i2c_adapter * > | i3c_master_to_i2c_adapter(struct i3c_master_controller *master) > | { > | return &master->i2c; > | } > > This means that `adap->name` should already be filled with NUL-bytes. > > 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> Looks right to me; straight replacement. Reviewed-by: Kees Cook <keescook@chromium.org>
On Thu, 21 Sep 2023 03:51:04 +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > We should prefer more robust and less ambiguous string interfaces. > > We expect adap->name to be NUL-terminated based on i2c_adapter name use: > | dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name); > > [...] Applied, thanks! [1/1] i3c: replace deprecated strncpy commit: fa7726a4d9b91e0a8fb6fbbd819cd20f116f6c21 Best regards,
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 87283e4a4607..8573ca507708 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -2309,7 +2309,7 @@ static int i3c_master_i2c_adapter_init(struct i3c_master_controller *master) adap->dev.parent = master->dev.parent; adap->owner = master->dev.parent->driver->owner; adap->algo = &i3c_master_i2c_algo; - strncpy(adap->name, dev_name(master->dev.parent), sizeof(adap->name)); + strscpy(adap->name, dev_name(master->dev.parent), sizeof(adap->name)); /* FIXME: Should we allow i3c masters to override these values? */ adap->timeout = 1000;
`strncpy` is deprecated for use on NUL-terminated destination strings [1]. We should prefer more robust and less ambiguous string interfaces. We expect adap->name to be NUL-terminated based on i2c_adapter name use: | dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name); NUL-padding does not seem to be required as `master` is zero-allocated and `i3c_master_to_i2c_adapter` simply returns a field from within `master`: | master = devm_kzalloc(dev, sizeof(*master), GFP_KERNEL); ... | struct i2c_adapter *adap = i3c_master_to_i2c_adapter(master); ... | static struct i2c_adapter * | i3c_master_to_i2c_adapter(struct i3c_master_controller *master) | { | return &master->i2c; | } This means that `adap->name` should already be filled with NUL-bytes. 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> --- drivers/i3c/master.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: 2cf0f715623872823a72e451243bbf555d10d032 change-id: 20230921-strncpy-drivers-i3c-master-c-d9e152a91aca Best regards, -- Justin Stitt <justinstitt@google.com>