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

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Message-ID: <159234276956.31057.6902954364435481688.stgit@gimli.home>
Date:   Tue, 16 Jun 2020 15:26:36 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     alex.williamson@...hat.com
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        cohuck@...hat.com, dwagner@...e.de, cai@....pw
Subject: [PATCH] vfio/pci: Clear error and request eventfd ctx after
 releasing

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>
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---
 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 7c0779018b1b..f634c81998bb 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -521,10 +521,14 @@ static void vfio_pci_release(void *device_data)
 		vfio_pci_vf_token_user_add(vdev, -1);
 		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(&vdev->reflck->lock);