crypto: s5p-sss: Fix race in error handling

Remove a race condition introduced by error path in functions:
s5p_aes_interrupt and s5p_aes_crypt_start. Setting the busy field of
struct s5p_aes_dev to false made it possible for s5p_tasklet_cb to
change the req field, before s5p_aes_complete was called.

Change the first parameter of s5p_aes_complete to struct
ablkcipher_request. Before spin_unlock, make a copy of the currently
handled request, to ensure s5p_aes_complete function call with the
correct request.
Signed-off-by: Christoph Manszewski <c.manszewski@samsung.com>
Acked-by: Kamil Konieczny <k.konieczny@partner.samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/s5p-sss.c

@@ -475,9 +475,9 @@ static void s5p_sg_done(struct s5p_aes_dev *dev)
 }
 
 /* Calls the completion. Cannot be called with dev->lock hold. */
-static void s5p_aes_complete(struct s5p_aes_dev *dev, int err)
+static void s5p_aes_complete(struct ablkcipher_request *req, int err)
 {
-	dev->req->base.complete(&dev->req->base, err);
+	req->base.complete(&req->base, err);
 }
 
 static void s5p_unset_outdata(struct s5p_aes_dev *dev)
@@ -655,6 +655,7 @@ static irqreturn_t s5p_aes_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = dev_id;
 	struct s5p_aes_dev *dev = platform_get_drvdata(pdev);
+	struct ablkcipher_request *req;
 	int err_dma_tx = 0;
 	int err_dma_rx = 0;
 	int err_dma_hx = 0;
@@ -727,7 +728,7 @@ static irqreturn_t s5p_aes_interrupt(int irq, void *dev_id)
 
 		spin_unlock_irqrestore(&dev->lock, flags);
 
-		s5p_aes_complete(dev, 0);
+		s5p_aes_complete(dev->req, 0);
 		/* Device is still busy */
 		tasklet_schedule(&dev->tasklet);
 	} else {
@@ -752,11 +753,12 @@ static irqreturn_t s5p_aes_interrupt(int irq, void *dev_id)
 error:
 	s5p_sg_done(dev);
 	dev->busy = false;
+	req = dev->req;
 	if (err_dma_hx == 1)
 		s5p_set_dma_hashdata(dev, dev->hash_sg_iter);
 
 	spin_unlock_irqrestore(&dev->lock, flags);
-	s5p_aes_complete(dev, err);
+	s5p_aes_complete(req, err);
 
 hash_irq_end:
 	/*
@@ -1983,7 +1985,7 @@ static void s5p_aes_crypt_start(struct s5p_aes_dev *dev, unsigned long mode)
 	s5p_sg_done(dev);
 	dev->busy = false;
 	spin_unlock_irqrestore(&dev->lock, flags);
-	s5p_aes_complete(dev, err);
+	s5p_aes_complete(req, err);
 }
 
 static void s5p_tasklet_cb(unsigned long data)