On 07/09/2019 06:16 AM, Cornelia Huck wrote:
On Mon, 8 Jul 2019 16:10:37 -0400
Farhan Ali <alifm@xxxxxxxxxxxxx> wrote:
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.
Can we pinpoint a commit that introduced this bug, or has it been there
since the beginning?
I think the problem was always there.
Signed-off-by: Farhan Ali <alifm@xxxxxxxxxxxxx>
---
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 4e3a903..0357165 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -92,7 +92,7 @@ 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);
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Thanks for reviewing.
Thanks
Farhan
