Patch "platform/mellanox: fix potential race in mlxbf-tmfifo driver" has been added to the 6.3-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    platform/mellanox: fix potential race in mlxbf-tmfifo driver

to the 6.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     platform-mellanox-fix-potential-race-in-mlxbf-tmfifo.patch
and it can be found in the queue-6.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9a03272d9a4c425184dc02fb0df9d6d40261778e
Author: Liming Sun <limings@xxxxxxxxxx>
Date:   Wed Apr 26 10:23:44 2023 -0400

    platform/mellanox: fix potential race in mlxbf-tmfifo driver
    
    [ Upstream commit 3d43f9f639542fadfb28f40b509bf147a6624d48 ]
    
    This commit adds memory barrier for the 'vq' update in function
    mlxbf_tmfifo_virtio_find_vqs() to avoid potential race due to
    out-of-order memory write. It also adds barrier for the 'is_ready'
    flag to make sure the initializations are visible before this flag
    is checked.
    
    Signed-off-by: Liming Sun <limings@xxxxxxxxxx>
    Reviewed-by: Vadim Pasternak <vadimp@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/b98c0ab61d644ba38fa9b3fd1607b138b0dd820b.1682518748.git.limings@xxxxxxxxxx
    Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c b/drivers/platform/mellanox/mlxbf-tmfifo.c
index 91a077c35b8b8..a79318e90a139 100644
--- a/drivers/platform/mellanox/mlxbf-tmfifo.c
+++ b/drivers/platform/mellanox/mlxbf-tmfifo.c
@@ -784,7 +784,7 @@ static void mlxbf_tmfifo_rxtx(struct mlxbf_tmfifo_vring *vring, bool is_rx)
 	fifo = vring->fifo;
 
 	/* Return if vdev is not ready. */
-	if (!fifo->vdev[devid])
+	if (!fifo || !fifo->vdev[devid])
 		return;
 
 	/* Return if another vring is running. */
@@ -980,9 +980,13 @@ static int mlxbf_tmfifo_virtio_find_vqs(struct virtio_device *vdev,
 
 		vq->num_max = vring->num;
 
+		vq->priv = vring;
+
+		/* Make vq update visible before using it. */
+		virtio_mb(false);
+
 		vqs[i] = vq;
 		vring->vq = vq;
-		vq->priv = vring;
 	}
 
 	return 0;
@@ -1302,6 +1306,9 @@ static int mlxbf_tmfifo_probe(struct platform_device *pdev)
 
 	mod_timer(&fifo->timer, jiffies + MLXBF_TMFIFO_TIMER_INTERVAL);
 
+	/* Make all updates visible before setting the 'is_ready' flag. */
+	virtio_mb(false);
+
 	fifo->is_ready = true;
 	return 0;