[PATCH v6 5/8] crypto: qce - Use fallback for fragmented skcipher payloads

[Bartosz Golaszewski]

The crypto engine reliably processes AES requests only when the payload
is a single contiguous buffer. A payload split across multiple
scatterlist entries makes the engine stall waiting for input, failing
the request with a hardware operation error. This was uncovered by the
crypto self-tests, which feed the algorithms randomly fragmented
buffers.

Detect a payload that spans more than one scatterlist entry, in either
the source or the destination, and route the request to the software
fallback.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 25b71d61d631 ("crypto: qce - Improve the conditions for requesting AES fallback cipher")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
---
 drivers/crypto/qce/skcipher.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/qce/skcipher.c b/drivers/crypto/qce/skcipher.c
index 54ff013e24317cd4d7a0dcde88cef8268db784c9..4779218d4f33a07331c510abf0d6d23e7e70d102 100644
--- a/drivers/crypto/qce/skcipher.c
+++ b/drivers/crypto/qce/skcipher.c
@@ -262,13 +262,17 @@ static int qce_skcipher_crypt(struct skcipher_request *req, int encrypt)
 	 * needed in all versions of CE)
 	 * AES-CTR with a partial final block (the CE stalls waiting for a full
 	 * block of input).
+	 * A payload fragmented across more than one scatterlist entry (the CE
+	 * stalls waiting for input in that case too).
 	 */
 	if (IS_AES(rctx->flags) &&
 	    ((keylen != AES_KEYSIZE_128 && keylen != AES_KEYSIZE_256) ||
 	    (IS_CTR(rctx->flags) && !IS_ALIGNED(req->cryptlen, AES_BLOCK_SIZE)) ||
 	    (IS_XTS(rctx->flags) && ((req->cryptlen <= aes_sw_max_len) ||
 	    (req->cryptlen > QCE_SECTOR_SIZE &&
-	    req->cryptlen % QCE_SECTOR_SIZE))))) {
+	    req->cryptlen % QCE_SECTOR_SIZE))) ||
+	    sg_nents_for_len(req->src, req->cryptlen) > 1 ||
+	    sg_nents_for_len(req->dst, req->cryptlen) > 1)) {
 		skcipher_request_set_tfm(&rctx->fallback_req, ctx->fallback);
 		skcipher_request_set_callback(&rctx->fallback_req,
 					      req->base.flags,

-- 
2.47.3