On Fri, Feb 23, 2024 at 10:23:10PM +0000, Justin Stitt wrote:
> Depending on the state of @compatible, we are going to do different
> things with our @to buffer.
>
> When @compatible is true we want a NUL-term'd and NUL-padded destination
> buffer. Conversely, if @compatible is false we just want a space-padded
> destination buffer (no NUL-term required).
>
> As per:
> /**
> * scsi_dev_info_list_add_keyed - add one dev_info list entry.
> * @compatible: if true, null terminate short strings. Otherwise space pad.
> ...
>
> Note that we can't easily use `strtomem_pad` here as the size of the @to
> buffer is unknown to the compiler due to indirection layers.
>
> Now, the intent of the code is more clear (I probably didn't even need
> to add a comment -- that's how clear it is).
>
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> drivers/scsi/scsi_devinfo.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/scsi/scsi_devinfo.c b/drivers/scsi/scsi_devinfo.c
> index 3fcaf10a9dfe..2d3dbce25629 100644
> --- a/drivers/scsi/scsi_devinfo.c
> +++ b/drivers/scsi/scsi_devinfo.c
> @@ -293,14 +293,16 @@ static void scsi_strcpy_devinfo(char *name, char *to, size_t to_length,
> size_t from_length;
>
> from_length = strlen(from);
> - /* This zero-pads the destination */
> - strncpy(to, from, to_length);
A rare case of the padding intent being expressed! :)
> - if (from_length < to_length && !compatible) {
> - /*
> - * space pad the string if it is short.
> - */
> - memset(&to[from_length], ' ', to_length - from_length);
> - }
> +
> + /*
> + * null pad and null terminate if compatible
> + * otherwise space pad
> + */
> + if (compatible)
> + strscpy_pad(to, from, to_length);
> + else
> + memcpy_and_pad(to, to_length, from, from_length, ' ');
Yeah, this is much nicer to read.
Reviewed-by: Kees Cook <[email protected]>
(Some day I want to rename "memcpy_and_pad" ... the "and" seems
verbose...)
--
Kees Cook