[PATCH 4.19 127/321] xen/pciback: Check dev_data before using it

[Greg Kroah-Hartman]

From: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>

[ Upstream commit 1669907e3d1abfa3f7586e2d55dbbc117b5adba2 ]

If pcistub_init_device fails, the release function will be called with
dev_data set to NULL.  Check it before using it to avoid a NULL pointer
dereference.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/xen/xen-pciback/pci_stub.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 59661db144e51..097410a7cdb74 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -106,7 +106,8 @@ static void pcistub_device_release(struct kref *kref)
 	 * is called from "unbind" which takes a device_lock mutex.
 	 */
 	__pci_reset_function_locked(dev);
-	if (pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state))
+	if (dev_data &&
+	    pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state))
 		dev_info(&dev->dev, "Could not reload PCI state\n");
 	else
 		pci_restore_state(dev);
-- 
2.20.1