[ Upstream commit f4c9939433bd396d0b08e803b2b880a9d02682b9 ]
There is a small window where it's possible that we could be working on an interrupt (queued in the workqueue) and setting up a channel program (i.e allocating memory, pinning pages, translating address). This can lead to allocating and freeing the channel program at the same time and can cause memory corruption.
Let's not call cp_free if we are currently processing a channel program. The only way we know for sure that we don't have a thread setting up a channel program is when the state is set to VFIO_CCW_STATE_CP_PENDING.
Fixes: d5afd5d135c8 ("vfio-ccw: add handling for async channel instructions") Signed-off-by: Farhan Ali alifm@linux.ibm.com Reviewed-by: Cornelia Huck cohuck@redhat.com Message-Id: 62e87bf67b38dc8d5760586e7c96d400db854ebe.1562854091.git.alifm@linux.ibm.com Reviewed-by: Eric Farman farman@linux.ibm.com Signed-off-by: Cornelia Huck cohuck@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/cio/vfio_ccw_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index 9125f7f4e64c9..8a8fbde7e1867 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -88,7 +88,7 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT)); if (scsw_is_solicited(&irb->scsw)) { cp_update_scsw(&private->cp, &irb->scsw); - if (is_final) + if (is_final && private->state == VFIO_CCW_STATE_CP_PENDING) cp_free(&private->cp); } mutex_lock(&private->io_mutex);