[PATCH v2 7/8] crypto: qce - Use a fallback for CCM with a partial final block

[Bartosz Golaszewski]

CCM builds on AES-CTR for encryption, and the crypto engine stalls on a
partial final block just as it does for plain ctr(aes): a payload whose
length is not a multiple of the AES block size leaves the operation
incomplete and fails with a hardware operation error. This was caught by
the ccm(aes) crypto self-tests.

Force the software fallback for CCM requests whose message length is not
block aligned, reusing the driver's existing need_fallback mechanism.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 9363efb4181c ("crypto: qce - Add support for AEAD algorithms")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
---
 drivers/crypto/qce/aead.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/crypto/qce/aead.c b/drivers/crypto/qce/aead.c
index 6a511e5d7f6290a1df0093e463f39f5f2db25f88..46d3e3eb53b271e2ce755847bbcc83f81b9bda7e 100644
--- a/drivers/crypto/qce/aead.c
+++ b/drivers/crypto/qce/aead.c
@@ -516,6 +516,14 @@ static int qce_aead_crypt(struct aead_request *req, int encrypt)
 			ctx->need_fallback = true;
 	}
 
+	/*
+	 * CCM uses AES-CTR internally and the CE stalls on a partial final
+	 * block, so a payload that is not a multiple of the block size has to
+	 * be handled by the fallback.
+	 */
+	if (IS_CCM(rctx->flags) && !IS_ALIGNED(rctx->cryptlen, AES_BLOCK_SIZE))
+		ctx->need_fallback = true;
+
 	/* If fallback is needed, schedule and exit */
 	if (ctx->need_fallback) {
 		/* Reset need_fallback in case the same ctx is used for another transaction */

-- 
2.47.3