crypto: marvell - properly handle CRYPTO_TFM_REQ_MAY_BACKLOG-flagged requests

The mv_cesa_queue_req() function calls crypto_enqueue_request() to
enqueue a request. In the normal case (i.e the queue isn't full), this
function returns -EINPROGRESS. The current Marvell CESA crypto driver
takes this into account and cleans up the request only if an error
occured, i.e if the return value is not -EINPROGRESS.

Unfortunately this causes problems with
CRYPTO_TFM_REQ_MAY_BACKLOG-flagged requests. When such a request is
passed to crypto_enqueue_request() and the queue is full,
crypto_enqueue_request() will return -EBUSY, but will keep the request
enqueued nonetheless. This situation was not properly handled by the
Marvell CESA driver, which was anyway cleaning up the request in such
a situation. When later on the request was taken out of the backlog
and actually processed, a kernel crash occured due to the internal
driver data structures for this structure having been cleaned up.

To avoid this situation, this commit adds a
mv_cesa_req_needs_cleanup() helper function which indicates if the
request needs to be cleaned up or not after a call to
crypto_enqueue_request(). This helper allows to do the cleanup only in
the appropriate cases, and all call sites of mv_cesa_queue_req() are
fixed to use this new helper function.

Reported-by: Vincent Donnefort <[e-mail]>
Fixes: db509a45339fd ("crypto: marvell/cesa - add TDMA support")
Cc: <[e-mail]> # v4.2+
Signed-off-by: Thomas Petazzoni <[e-mail]>
Acked-by: Boris Brezillon <[e-mail]>
Tested-by: Vincent Donnefort <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/marvell/cesa.h

···
 
 int mv_cesa_queue_req(struct crypto_async_request *req);
 
+/*
+ * Helper function that indicates whether a crypto request needs to be
+ * cleaned up or not after being enqueued using mv_cesa_queue_req().
+ */
+static inline int mv_cesa_req_needs_cleanup(struct crypto_async_request *req,
+					    int ret)
+{
+	/*
+	 * The queue still had some space, the request was queued
+	 * normally, so there's no need to clean it up.
+	 */
+	if (ret == -EINPROGRESS)
+		return false;
+
+	/*
+	 * The queue had not space left, but since the request is
+	 * flagged with CRYPTO_TFM_REQ_MAY_BACKLOG, it was added to
+	 * the backlog and will be processed later. There's no need to
+	 * clean it up.
+	 */
+	if (ret == -EBUSY && req->flags & CRYPTO_TFM_REQ_MAY_BACKLOG)
+		return false;
+
+	/* Request wasn't queued, we need to clean it up */
+	return true;
+}
+
 /* TDMA functions */
 
 static inline void mv_cesa_req_dma_iter_init(struct mv_cesa_dma_iter *iter,

drivers/crypto/marvell/cipher.c

···
 {
 	struct ablkcipher_request *ablkreq = ablkcipher_request_cast(req);
 	struct mv_cesa_ablkcipher_req *creq = ablkcipher_request_ctx(ablkreq);
-
 	creq->req.base.engine = engine;
 
 	if (creq->req.base.type == CESA_DMA_REQ)
···
 		return ret;
 
 	ret = mv_cesa_queue_req(&req->base);
-	if (ret && ret != -EINPROGRESS)
+	if (mv_cesa_req_needs_cleanup(&req->base, ret))
 		mv_cesa_ablkcipher_cleanup(req);
 
 	return ret;
···
 		return ret;
 
 	ret = mv_cesa_queue_req(&req->base);
-	if (ret && ret != -EINPROGRESS)
+	if (mv_cesa_req_needs_cleanup(&req->base, ret))
 		mv_cesa_ablkcipher_cleanup(req);
 
 	return ret;
···
 		return ret;
 
 	ret = mv_cesa_queue_req(&req->base);
-	if (ret && ret != -EINPROGRESS)
+	if (mv_cesa_req_needs_cleanup(&req->base, ret))
 		mv_cesa_ablkcipher_cleanup(req);
 
 	return ret;

drivers/crypto/marvell/hash.c

···
 		return 0;
 
 	ret = mv_cesa_queue_req(&req->base);
-	if (ret && ret != -EINPROGRESS) {
+	if (mv_cesa_req_needs_cleanup(&req->base, ret))
 		mv_cesa_ahash_cleanup(req);
-		return ret;
-	}
 
 	return ret;
 }
···
 		return 0;
 
 	ret = mv_cesa_queue_req(&req->base);
-	if (ret && ret != -EINPROGRESS)
+	if (mv_cesa_req_needs_cleanup(&req->base, ret))
 		mv_cesa_ahash_cleanup(req);
 
 	return ret;
···
 		return 0;
 
 	ret = mv_cesa_queue_req(&req->base);
-	if (ret && ret != -EINPROGRESS)
+	if (mv_cesa_req_needs_cleanup(&req->base, ret))
 		mv_cesa_ahash_cleanup(req);
 
 	return ret;