linux-kernel - [PATCH 5.4 123/191] dmaengine: virt-dma: Fix access after free in vchan

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Date:   Tue,  7 Jan 2020 21:54:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Peter Ujfalusi <peter.ujfalusi@...com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Vinod Koul <vkoul@...nel.org>
Subject: [PATCH 5.4 123/191] dmaengine: virt-dma: Fix access after free in vchan_complete()

From: Peter Ujfalusi <peter.ujfalusi@...com>

commit 24461d9792c2c706092805ff1b067628933441bd upstream.

vchan_vdesc_fini() is freeing up 'vd' so the access to vd->tx_result is
via already freed up memory.

Move the vchan_vdesc_fini() after invoking the callback to avoid this.

Fixes: 09d5b702b0f97 ("dmaengine: virt-dma: store result on dma descriptor")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
Link: https://lore.kernel.org/r/20191220131100.21804-1-peter.ujfalusi@ti.com
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/dma/virt-dma.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/dma/virt-dma.c
+++ b/drivers/dma/virt-dma.c
@@ -104,9 +104,8 @@ static void vchan_complete(unsigned long
 		dmaengine_desc_get_callback(&vd->tx, &cb);
 
 		list_del(&vd->node);
-		vchan_vdesc_fini(vd);
-
 		dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
+		vchan_vdesc_fini(vd);
 	}
 }