Commit e0f6974a authored Aug 02, 2019 by Roderick Colenbrander Committed by Jiri Kosina Aug 06, 2019

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: Roderick Colenbrander <roderick.colenbrander@sony.com>
CC: stable@vger.kernel.org
Signed-off-by: Jiri 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)

Admin message