[PATCH] driver core: auxiliary bus: Fix auxiliary bus shutdown null auxdrv ptr

[Dave Jiang]

If the probe of the auxdrv failed, the device->driver is set to NULL.
During kernel shutdown, the bus shutdown will call auxdrv->shutdown and
cause an invalid ptr dereference. Add check to make sure device->driver is
not NULL before we proceed.

Fixes: 7de3697e9cbd ("Add auxiliary bus support")
Cc: Dave Ertman <david.m.ert...@intel.com>
Signed-off-by: Dave Jiang <dave.ji...@intel.com>
Reviewed-by: Dan Williams <dan.j.willi...@intel.com>
---
 drivers/base/auxiliary.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c
index f303daadf843..8336535f1e11 100644
--- a/drivers/base/auxiliary.c
+++ b/drivers/base/auxiliary.c
@@ -92,10 +92,15 @@ static int auxiliary_bus_remove(struct device *dev)
 
 static void auxiliary_bus_shutdown(struct device *dev)
 {
-       struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
-       struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
+       struct auxiliary_driver *auxdrv = NULL;
+       struct auxiliary_device *auxdev;
+
+       if (dev->driver) {
+               auxdrv = to_auxiliary_drv(dev->driver);
+               auxdev = to_auxiliary_dev(dev);
+       }
 
-       if (auxdrv->shutdown)
+       if (auxdrv && auxdrv->shutdown)
                auxdrv->shutdown(auxdev);
 }