efi_loader: pkcs7_parse_message() returns error pointer

Heinrich Schuchardt
2020-05-07T16:02:31Z

On 07.05.20 02:17, Patrick Wildt wrote:
> Since pkcs7_parse_message() returns an error pointer, we must not
> check for NULL. We have to explicitly set msg to NULL in the error
> case, otherwise the call to pkcs7_free_message() on the goto err
> path will assume it's a valid object.
>
> Signed-off-by: Patrick Wildt <patrick@blueri.se>
>
> diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
> index 5a9a6424cc..43a53d3dd1 100644
> --- a/lib/efi_loader/efi_image_loader.c
> +++ b/lib/efi_loader/efi_image_loader.c
> @@ -538,8 +538,9 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
> }
> msg = pkcs7_parse_message((void *)wincert + sizeof(*wincert),
> wincert->dwLength - sizeof(*wincert));
> - if (!msg) {
> + if (IS_ERR(msg)) {

Compiling with sandbox_defconfig results in:

lib/efi_loader/efi_image_loader.c: In function ?efi_image_authenticate?:
lib/efi_loader/efi_image_loader.c:541:7: warning: implicit declaration
of function ?IS_ERR? [-Wimplicit-function-declaration]
541 | if (IS_ERR(msg)) {
| ^~~~~~

I will add the missing #include <linux/err.h> when merging.

Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

> debug("Parsing image's signature failed\n");
> + msg = NULL;
> goto err;
> }
>
>