[PATCH] atmel: fix an error handle in mxt_probe

[Pan Xinhui]

mxt_probe() may fail at last step, and the queue_work scheduled by request_firmware_nowait
may run later and then access some data which is freed.
To handle this error, add one mutex_lock to cover such case. It may cause module load delay only when the probe fails.

here is the detail.

module load:                                                             worker_thread:
mxt_probe -> mxt_initialize -> request_firmware_nowait (schedule_work)
                   |
            sysfs_create_group (fails)                                    mxt_config_cb -> mxt_configure_objects (may access data freed)
                   |
            err_free_object: some cleanup work, like free(data).

Signed-off-by: xinhuix.pan <xinhuix.pan@xxxxxxxxx>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 2875ddf..af057c0 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -1978,10 +1978,19 @@ err_free_mem:
 static int mxt_configure_objects(struct mxt_data *data,
 				 const struct firmware *cfg);
 
+static DEFINE_MUTEX(err_probe_lock);
+static int err_probe;
+
 static void mxt_config_cb(const struct firmware *cfg, void *ctx)
 {
+	mutex_lock(&err_probe_lock);
+	if (err_probe) {
+		mutex_unlock(&err_probe_lock);
+		return;
+	}
 	mxt_configure_objects(ctx, cfg);
 	release_firmware(cfg);
+	mutex_unlock(&err_probe_lock);
 }
 
 static int mxt_initialize(struct mxt_data *data)
@@ -2423,6 +2432,8 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	const struct mxt_platform_data *pdata;
 	int error;
 
+	err_probe = 0;
+
 	pdata = dev_get_platdata(&client->dev);
 	if (!pdata) {
 		pdata = mxt_parse_dt(client);
@@ -2472,6 +2483,9 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	return 0;
 
 err_free_object:
+	mutex_lock(&err_probe_lock);
+	err_probe = -1;
+	mutex_unlock(&err_probe_lock);
 	mxt_free_input_device(data);
 	mxt_free_object_table(data);
 err_free_irq:
--
1.9.1
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