linux-kernel - [PATCH 4.4 71/85] vfio/pci: Clear error and request eventfd ctx after releasing

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Date:   Tue, 29 Sep 2020 13:00:38 +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, Qian Cai <cai@....pw>,
        Daniel Wagner <dwagner@...e.de>,
        Cornelia Huck <cohuck@...hat.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 71/85] vfio/pci: Clear error and request eventfd ctx after releasing

From: Alex Williamson <alex.williamson@...hat.com>

[ Upstream commit 5c5866c593bbd444d0339ede6a8fb5f14ff66d72 ]

The next use of the device will generate an underflow from the
stale reference.

Cc: Qian Cai <cai@....pw>
Fixes: 1518ac272e78 ("vfio/pci: fix memory leaks of eventfd ctx")
Reported-by: Daniel Wagner <dwagner@...e.de>
Reviewed-by: Cornelia Huck <cohuck@...hat.com>
Tested-by: Daniel Wagner <dwagner@...e.de>
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/vfio/pci/vfio_pci.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index ab765770e8dd6..662ea7ec82926 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -255,10 +255,14 @@ static void vfio_pci_release(void *device_data)
 	if (!(--vdev->refcnt)) {
 		vfio_spapr_pci_eeh_release(vdev->pdev);
 		vfio_pci_disable(vdev);
-		if (vdev->err_trigger)
+		if (vdev->err_trigger) {
 			eventfd_ctx_put(vdev->err_trigger);
-		if (vdev->req_trigger)
+			vdev->err_trigger = NULL;
+		}
+		if (vdev->req_trigger) {
 			eventfd_ctx_put(vdev->req_trigger);
+			vdev->req_trigger = NULL;
+		}
 	}
 
 	mutex_unlock(&driver_lock);
-- 
2.25.1