[lvc-project] [PATCH] Drivers: hv: vmbus: Fix potential NULL pointer dereference in vmbus_acpi_add()

[Ваторопин Андрей]

From: Andrey Vatoropin <a.vatoropin at crpt.ru>

The current driver supports detection via both the ACPI interface and the
Device Tree interface (OF).

In the function vmbus_platform_driver_probe() upon driver detection via OF,
the branch vmbus_device_add() should be executed.

However, the variable "acpi_disabled" is a global variable that, in general
equals 0 when CONFIG_ACPI is enabled. Therefore, it may enter another
branch with vmbus_acpi_add().

Therefore, in the function vmbus_acpi_add(), when the device is not ACPI,
the ACPI_COMPANION macro may return a NULL value, and this pointer is then
dereferenced.

Add a NULL pointer check for the "device" pointer before dereferencing it.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: f83705a51275 ("Driver: VMBus: Add Devicetree support")
Cc: stable at vger.kernel.org
Signed-off-by: Andrey Vatoropin <a.vatoropin at crpt.ru>
---
 drivers/hv/vmbus_drv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index bc4fc1951ae1..c9ee3375b524 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2571,6 +2571,9 @@ static int vmbus_acpi_add(struct platform_device *pdev)
 	struct acpi_device *ancestor;
 	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 
+	if (!device)
+		return -ENODEV;
+
 	vmbus_root_device = &device->dev;
 
 	/*
-- 
2.43.0