[PATCH 16/22] crypto: ccree - add check for xts input length equal to zero

[Andrei Botila]

From: Andrei Botila <andrei.botila@xxxxxxx>

Standardize the way input lengths equal to 0 are handled in all skcipher
algorithms. All the algorithms return 0 for input lengths equal to zero.
This change has implications not only for xts(aes) but also for cts(cbc(aes))
and cts(cbc(paes)).

Cc: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>
Signed-off-by: Andrei Botila <andrei.botila@xxxxxxx>
---
 drivers/crypto/ccree/cc_cipher.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/crypto/ccree/cc_cipher.c b/drivers/crypto/ccree/cc_cipher.c
index 076669dc1035..112bb8b4dce6 100644
--- a/drivers/crypto/ccree/cc_cipher.c
+++ b/drivers/crypto/ccree/cc_cipher.c
@@ -912,17 +912,18 @@ static int cc_cipher_process(struct skcipher_request *req,
 
 	/* STAT_PHASE_0: Init and sanity checks */
 
-	if (validate_data_size(ctx_p, nbytes)) {
-		dev_dbg(dev, "Unsupported data size %d.\n", nbytes);
-		rc = -EINVAL;
-		goto exit_process;
-	}
 	if (nbytes == 0) {
 		/* No data to process is valid */
 		rc = 0;
 		goto exit_process;
 	}
 
+	if (validate_data_size(ctx_p, nbytes)) {
+		dev_dbg(dev, "Unsupported data size %d.\n", nbytes);
+		rc = -EINVAL;
+		goto exit_process;
+	}
+
 	if (ctx_p->fallback_on) {
 		struct skcipher_request *subreq = skcipher_request_ctx(req);
 
-- 
2.17.1