[PATCH v2 05/12] usb: otg-fsm: Fix hrtimer list corruption

[Dmitry Osipenko]

The HNP work can be re-scheduled while it's still in-fly. This results in
re-initialization of the busy work, resetting the hrtimer's list node of
the work and crashing kernel with null dereference within kernel/timer
once work's timer is expired. It's very easy to trigger this problem by
re-plugging USB cable quickly. Initialize HNP work only once to fix this
trouble.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
 drivers/usb/common/usb-otg-fsm.c | 6 +++++-
 include/linux/usb/otg-fsm.h      | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/common/usb-otg-fsm.c b/drivers/usb/common/usb-otg-fsm.c
index 3740cf95560e..0697fde51d00 100644
--- a/drivers/usb/common/usb-otg-fsm.c
+++ b/drivers/usb/common/usb-otg-fsm.c
@@ -193,7 +193,11 @@ static void otg_start_hnp_polling(struct otg_fsm *fsm)
 	if (!fsm->host_req_flag)
 		return;
 
-	INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work);
+	if (!fsm->hnp_work_inited) {
+		INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work);
+		fsm->hnp_work_inited = true;
+	}
+
 	schedule_delayed_work(&fsm->hnp_polling_work,
 					msecs_to_jiffies(T_HOST_REQ_POLL));
 }
diff --git a/include/linux/usb/otg-fsm.h b/include/linux/usb/otg-fsm.h
index 3aee78dda16d..784659d4dc99 100644
--- a/include/linux/usb/otg-fsm.h
+++ b/include/linux/usb/otg-fsm.h
@@ -196,6 +196,7 @@ struct otg_fsm {
 	struct mutex lock;
 	u8 *host_req_flag;
 	struct delayed_work hnp_polling_work;
+	bool hnp_work_inited;
 	bool state_changed;
 };
 
-- 
2.30.2