[PATCH 2/2] crypto: atmel-sha - fix race in atmel_sha_final()

From: Cyrille Pitchen
Date: Mon Feb 08 2016 - 10:26:51 EST


When (!ctx->bufcnt && !(ctx->flags & SHA_FLAGS_PAD)), the former source
code used to set the SHA_FLAGS_BUSY without checking whether this flag was
already set. If so, the hardware is already processing another hash
request so the processing of the req argument of atmel_sha_final() should
be delayed by queueing this request, the same way as done for the
(ctx->bufcnt != 0) case.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
---
drivers/crypto/atmel-sha.c | 24 ++----------------------
1 file changed, 2 insertions(+), 22 deletions(-)

diff --git a/drivers/crypto/atmel-sha.c b/drivers/crypto/atmel-sha.c
index 7d27f96cdf02..596e489a4ca9 100644
--- a/drivers/crypto/atmel-sha.c
+++ b/drivers/crypto/atmel-sha.c
@@ -979,37 +979,17 @@ static int atmel_sha_update(struct ahash_request *req)
static int atmel_sha_final(struct ahash_request *req)
{
struct atmel_sha_reqctx *ctx = ahash_request_ctx(req);
- struct atmel_sha_ctx *tctx = crypto_tfm_ctx(req->base.tfm);
- struct atmel_sha_dev *dd = tctx->dd;
-
- int err = 0;

ctx->flags |= SHA_FLAGS_FINUP;

if (ctx->flags & SHA_FLAGS_ERROR)
return 0; /* uncompleted hash is not needed */

- if (ctx->bufcnt) {
- return atmel_sha_enqueue(req, SHA_OP_FINAL);
- } else if (!(ctx->flags & SHA_FLAGS_PAD)) { /* add padding */
- err = atmel_sha_hw_init(dd);
- if (err)
- goto err1;
-
- dd->req = req;
- dd->flags |= SHA_FLAGS_BUSY;
- err = atmel_sha_final_req(dd);
- } else {
+ if (ctx->flags & SHA_FLAGS_PAD)
/* copy ready hash (+ finalize hmac) */
return atmel_sha_finish(req);
- }
-
-err1:
- if (err != -EINPROGRESS)
- /* done_task will not finish it, so do it here */
- atmel_sha_finish_req(req, err);

- return err;
+ return atmel_sha_enqueue(req, SHA_OP_FINAL);
}

static int atmel_sha_finup(struct ahash_request *req)
--
1.8.2.2