On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote:
> Avoid leaking GCM tag through timing side channel.
>
> Signed-off-by: Cfir Cohen <c...@google.com>
> ---
> drivers/crypto/ccp/ccp-ops.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
> index db8de89d990f..633670220f6c 100644
> --- a/drivers/crypto/ccp/ccp-ops.c
> +++ b/drivers/crypto/ccp/ccp-ops.c
> @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue
> *cmd_q,
> if (ret)
> goto e_tag;
>
> - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE);
> + ret = crypto_memneq(tag.address, final_wa.address,
> + AES_BLOCK_SIZE) ? -EBADMSG : 0;
> ccp_dm_free(&tag);
> }
>
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
Looks like this needs:
Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5
CCPs")
Cc: <sta...@vger.kernel.org> # v4.12+
- Eric
