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Commit e0f6974a authored by Roderick Colenbrander's avatar Roderick Colenbrander Committed by Jiri Kosina
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HID: sony: Fix race condition between rumble and device remove. 



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: default avatarRoderick Colenbrander <roderick.colenbrander@sony.com>
CC: stable@vger.kernel.org
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 6d4472d7

drivers/hid/hid-sony.c

+12 −3
Original line number Diff line number Diff line
@@ -585,10 +585,14 @@ 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)
@@ -2558,12 +2562,17 @@ 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)