[PATCH 4.14 03/69] crypto: ccp - Ignore tag length when decrypting GCM ciphertext

From: Greg Kroah-Hartman
Date: Wed Aug 14 2019 - 13:12:38 EST


From: Gary R Hook <gary.hook@xxxxxxx>

commit e2664ecbb2f26225ac6646876f2899558ffb2604 upstream.

AES GCM input buffers for decryption contain AAD+CTEXT+TAG. Only
decrypt the ciphertext, and use the tag for comparison.

Fixes: 36cf515b9bbe2 ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Gary R Hook <gary.hook@xxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/crypto/ccp/ccp-ops.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/crypto/ccp/ccp-ops.c
+++ b/drivers/crypto/ccp/ccp-ops.c
@@ -752,8 +752,7 @@ static int ccp_run_aes_gcm_cmd(struct cc
while (src.sg_wa.bytes_left) {
ccp_prepare_data(&src, &dst, &op, AES_BLOCK_SIZE, true);
if (!src.sg_wa.bytes_left) {
- unsigned int nbytes = aes->src_len
- % AES_BLOCK_SIZE;
+ unsigned int nbytes = ilen % AES_BLOCK_SIZE;

if (nbytes) {
op.eom = 1;