Re: [PATCH 10/11] staging: greybus: change strncpy() to strscpy()

[Dan Carpenter]

On Thu, Mar 28, 2024 at 03:04:54PM +0100, Arnd Bergmann wrote:
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> This is from randconfig testing with random gcc versions, a .config to
> reproduce is at https://pastebin.com/r13yezkU
> ---
>  drivers/staging/greybus/fw-management.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/greybus/fw-management.c
> index 3054f084d777..35bfdd5f32d2 100644
> --- a/drivers/staging/greybus/fw-management.c
> +++ b/drivers/staging/greybus/fw-management.c
> @@ -303,13 +303,13 @@ static int fw_mgmt_backend_fw_update_operation(struct fw_mgmt *fw_mgmt,
>  	struct gb_fw_mgmt_backend_fw_update_request request;
>  	int ret;
>  
> -	strncpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE);
> +	ret = strscpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE);

This needs to be strscpy_pad() or it risks an information leak.

>  
>  	/*
>  	 * The firmware-tag should be NULL terminated, otherwise throw error and
                                      ^^^^^^^^^^^^^^^^
These comments are out of date.

>  	 * fail.
>  	 */
> -	if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') {
> +	if (ret == -E2BIG) {
>  		dev_err(fw_mgmt->parent, "backend-update: firmware-tag is not NULL terminated\n");
                                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
More out of date prints.

regards,
dan carpenter