crypto: ahash - Zero positive err value in ahash_update_finish

The partial block length returned by a block-only driver should
not be passed up to the caller since ahash itself deals with the
partial block data.

Set err to zero in ahash_update_finish if it was positive.

Reported-by: T Pratham <t-pratham@ti.com>
Tested-by: T Pratham <t-pratham@ti.com>
Fixes: 9d7a0ab ("crypto: ahash - Handle partial blocks in API")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Author: herbertx

crypto/ahash.c

@@ -423,7 +423,11 @@ static int ahash_update_finish(struct ahash_request *req, int err)
 
 	req->nbytes += nonzero - blen;
 
-	blen = err < 0 ? 0 : err + nonzero;
+	blen = 0;
+	if (err >= 0) {
+		blen = err + nonzero;
+		err = 0;
+	}
 	if (ahash_request_isvirt(req))
 		memcpy(buf, req->svirt + req->nbytes - blen, blen);
 	else