Valve reported a kernel crash on Ubuntu 18.04 when disconnecting a DS4
gamepad while rumble is enabled. This issue is reproducible with a
frequency of 1 in 3 times in the game Borderlands 2 when using an
automatic weapon, which triggers many rumble operations.
We found the issue to be a race condition between sony_remove and the
final device destruction by the HID / input system. The problem was
that sony_remove didn't clean some of its work_item state in
"struct sony_sc". After sony_remove work, the corresponding evdev
node was around for sufficient time for applications to still queue
rumble work after "sony_remove".
On pre-4.19 kernels the race condition caused a kernel crash due to a
NULL-pointer dereference as "sc->output_report_dmabuf" got freed during
sony_remove. On newer kernels this crash doesn't happen due the buffer
now being allocated using devm_kzalloc. However we can still queue work,
while the driver is an undefined state.
This patch fixes the described problem, by guarding the work_item
"state_worker" with an initialized variable, which we are setting back
to 0 on cleanup.
Signed-off-by: Roderick Colenbrander <roderick.colenbrander@xxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx
---
drivers/hid/hid-sony.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/hid/hid-sony.c b/drivers/hid/hid-sony.c
index 9671a4bad643..31f1023214d3 100644
--- a/drivers/hid/hid-sony.c
+++ b/drivers/hid/hid-sony.c
@@ -587,10 +587,14 @@ static void sony_set_leds(struct sony_sc *sc);
static inline void sony_schedule_work(struct sony_sc *sc,
enum sony_worker which)
{
+ unsigned long flags;
+
switch (which) {
case SONY_WORKER_STATE:
- if (!sc->defer_initialization)
+ spin_lock_irqsave(&sc->lock, flags);
+ if (!sc->defer_initialization && sc->state_worker_initialized)
schedule_work(&sc->state_worker);
+ spin_unlock_irqrestore(&sc->lock, flags);
break;
case SONY_WORKER_HOTPLUG:
if (sc->hotplug_worker_initialized)
@@ -2553,13 +2557,18 @@ static inline void sony_init_output_report(struct sony_sc *sc,
static inline void sony_cancel_work_sync(struct sony_sc *sc)
{
+ unsigned long flags;
+
if (sc->hotplug_worker_initialized)
cancel_work_sync(&sc->hotplug_worker);
- if (sc->state_worker_initialized)
+ if (sc->state_worker_initialized) {
+ spin_lock_irqsave(&sc->lock, flags);
+ sc->state_worker_initialized = 0;
+ spin_unlock_irqrestore(&sc->lock, flags);
cancel_work_sync(&sc->state_worker);
+ }
}
-
static int sony_input_configured(struct hid_device *hdev,
struct hid_input *hidinput)
{
--
2.21.0
