s390/cio: verify the driver availability for path_event call

commit dd9cb842fa9d90653a9b48aba52f89c069f3bc50 upstream.

If no driver is attached to a device or the driver does not provide the
path_event function, an FCES path-event on this device could end up in a
kernel-panic. Verify the driver availability before the path_event
function call.

Fixes: 32ef938815c1 ("s390/cio: Add support for FCES status notification")
Cc: stable@vger.kernel.org
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Suggested-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 8d14569..61cde02 100644 (file)
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -1194,7 +1194,7 @@ static int io_subchannel_chp_event(struct subchannel *sch,
                        else
                                path_event[chpid] = PE_NONE;
                }
-               if (cdev)
+               if (cdev && cdev->drv && cdev->drv->path_event)
                        cdev->drv->path_event(cdev, path_event);
                break;
        }