[PATCH] input: synaptics_i2c - cancel delayed work before freeing device

[Minseong Kim <ii4gsp@gmail.com>]

synaptics_i2c_irq() schedules touch->dwork via mod_delayed_work().
The delayed work performs I2C transactions and may still be running
(or get queued) when the device is removed.

synaptics_i2c_remove() currently frees 'touch' without canceling
touch->dwork. If removal happens while the work is pending/running,
the work handler may dereference freed memory, leading to a potential
use-after-free.

Cancel the delayed work synchronously before unregistering/freeing
the device.

Fixes: eef3e4cab72e Input: add driver for Synaptics I2C touchpad
Reported-by: Minseong Kim <ii4gsp@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Minseong Kim <ii4gsp@gmail.com>
---
 drivers/input/mouse/synaptics_i2c.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/input/mouse/synaptics_i2c.c b/drivers/input/mouse/synaptics_i2c.c
index a0d707e47d93..fe30bf9aea3a 100644
--- a/drivers/input/mouse/synaptics_i2c.c
+++ b/drivers/input/mouse/synaptics_i2c.c
@@ -593,6 +593,8 @@ static void synaptics_i2c_remove(struct i2c_client *client)
 	if (!polling_req)
 		free_irq(client->irq, touch);
 
+	cancel_delayed_work_sync(&touch->dwork);
+
 	input_unregister_device(touch->input);
 	kfree(touch);
 }
-- 
2.39.5