linux-kernel - [PATCH 4.11 033/114] crypto: s5p-sss - Close possible race for completed requests

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Date:   Thu, 18 May 2017 12:45:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Krzysztof Kozlowski <krzk@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH 4.11 033/114] crypto: s5p-sss - Close possible race for completed requests

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Krzysztof Kozlowski <krzk@...nel.org>

commit 42d5c176b76e190a4a3e0dfeffdae661755955b6 upstream.

Driver is capable of handling only one request at a time and it stores
it in its state container struct s5p_aes_dev.  This stored request must be
protected between concurrent invocations (e.g. completing current
request and scheduling new one).  Combination of lock and "busy" field
is used for that purpose.

When "busy" field is true, the driver will not accept new request thus
it will not overwrite currently handled data.

However commit 28b62b145868 ("crypto: s5p-sss - Fix spinlock recursion
on LRW(AES)") moved some of the write to "busy" field out of a lock
protected critical section.  This might lead to potential race between
completing current request and scheduling a new one.  Effectively the
request completion might try to operate on new crypto request.

Fixes: 28b62b145868 ("crypto: s5p-sss - Fix spinlock recursion on LRW(AES)")
Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/crypto/s5p-sss.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/crypto/s5p-sss.c
+++ b/drivers/crypto/s5p-sss.c
@@ -287,7 +287,6 @@ static void s5p_sg_done(struct s5p_aes_d
 static void s5p_aes_complete(struct s5p_aes_dev *dev, int err)
 {
 	dev->req->base.complete(&dev->req->base, err);
-	dev->busy = false;
 }

 static void s5p_unset_outdata(struct s5p_aes_dev *dev)
@@ -462,7 +461,7 @@ static irqreturn_t s5p_aes_interrupt(int
 		spin_unlock_irqrestore(&dev->lock, flags);

 		s5p_aes_complete(dev, 0);
-		dev->busy = true;
+		/* Device is still busy */
 		tasklet_schedule(&dev->tasklet);
 	} else {
 		/*
@@ -483,6 +482,7 @@ static irqreturn_t s5p_aes_interrupt(int

 error:
 	s5p_sg_done(dev);
+	dev->busy = false;
 	spin_unlock_irqrestore(&dev->lock, flags);
 	s5p_aes_complete(dev, err);

@@ -634,6 +634,7 @@ outdata_error:

 indata_error:
 	s5p_sg_done(dev);
+	dev->busy = false;
 	spin_unlock_irqrestore(&dev->lock, flags);
 	s5p_aes_complete(dev, err);
 }