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SubjectRe: [PATCH] i3c: replace deprecated strncpy
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>

--
Kees Cook

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