On 7/2/19 12:32 PM, Cfir Cohen wrote:

Avoid leaking GCM tag through timing side channel.

Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Cfir Cohen cfir@google.com

Acked-by: Gary R Hook ghook@amd.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); }