Re: [PATCH 1/2] efi_loader: fix efi_get_next_variable_name_mem()

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

On Sun, Dec 18, 2022 at 06:08:57AM +0000, Heinrich Schuchardt wrote:
> The VariableNameSize parameter is in bytes but u16_strnlen() counts u16.
>
> Fix the parameter check for null termination.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> ---
>  include/efi_variable.h       | 3 ++-
>  lib/efi_loader/efi_var_mem.c | 6 +++---
>  2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/include/efi_variable.h b/include/efi_variable.h
> index 03a3ecb235..805e6c5f1e 100644
> --- a/include/efi_variable.h
> +++ b/include/efi_variable.h
> @@ -268,7 +268,8 @@ const efi_guid_t *efi_auth_var_get_guid(const u16 *name);
>   * efi_get_next_variable_name_mem() - Runtime common code across efi variable
>   *                                    implementations for GetNextVariable()
>   *                                    from the cached memory copy
> - * @variable_name_size:	size of variable_name buffer in byte
> + *
> + * @variable_name_size:	size of variable_name buffer in bytes
>   * @variable_name:	name of uefi variable's name in u16
>   * @vendor:		vendor's guid
>   *
> diff --git a/lib/efi_loader/efi_var_mem.c b/lib/efi_loader/efi_var_mem.c
> index 13909b1d26..0bac594e00 100644
> --- a/lib/efi_loader/efi_var_mem.c
> +++ b/lib/efi_loader/efi_var_mem.c
> @@ -315,14 +315,14 @@ efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size,
>  			       u16 *variable_name, efi_guid_t *vendor)
>  {
>  	struct efi_var_entry *var;
> -	efi_uintn_t old_size;
> +	efi_uintn_t len, old_size;
>  	u16 *pdata;
>
>  	if (!variable_name_size || !variable_name || !vendor)
>  		return EFI_INVALID_PARAMETER;
>
> -	if (u16_strnlen(variable_name, *variable_name_size) ==
> -	    *variable_name_size)
> +	len = *variable_name_size >> 1;
> +	if (u16_strnlen(variable_name, len) == len)
>  		return EFI_INVALID_PARAMETER;
>
>  	if (!efi_var_mem_find(vendor, variable_name, &var) && *variable_name)
> --
> 2.37.2
>


Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>