[media] cx25840: fix unchecked return values

In functions cx25840_initialize(), cx231xx_initialize(), and
cx23885_initialize(), the return value of create_singlethread_workqueue()
is used without validation. This may result in NULL dereference and cause
kernel crash. This patch fixes it.

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/i2c/cx25840/cx25840-core.c b/drivers/media/i2c/cx25840/cx25840-core.c
index b8d3c07..39f51da 100644 (file)
--- a/drivers/media/i2c/cx25840/cx25840-core.c
+++ b/drivers/media/i2c/cx25840/cx25840-core.c
@@ -416,11 +416,13 @@ static void cx25840_initialize(struct i2c_client *client)
        INIT_WORK(&state->fw_work, cx25840_work_handler);
        init_waitqueue_head(&state->fw_wait);
        q = create_singlethread_workqueue("cx25840_fw");
-       prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
-       queue_work(q, &state->fw_work);
-       schedule();
-       finish_wait(&state->fw_wait, &wait);
-       destroy_workqueue(q);
+       if (q) {
+               prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
+               queue_work(q, &state->fw_work);
+               schedule();
+               finish_wait(&state->fw_wait, &wait);
+               destroy_workqueue(q);
+       }
 
        /* 6. */
        cx25840_write(client, 0x115, 0x8c);
@@ -630,11 +632,13 @@ static void cx23885_initialize(struct i2c_client *client)
        INIT_WORK(&state->fw_work, cx25840_work_handler);
        init_waitqueue_head(&state->fw_wait);
        q = create_singlethread_workqueue("cx25840_fw");
-       prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
-       queue_work(q, &state->fw_work);
-       schedule();
-       finish_wait(&state->fw_wait, &wait);
-       destroy_workqueue(q);
+       if (q) {
+               prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
+               queue_work(q, &state->fw_work);
+               schedule();
+               finish_wait(&state->fw_wait, &wait);
+               destroy_workqueue(q);
+       }
 
        /* Call the cx23888 specific std setup func, we no longer rely on
         * the generic cx24840 func.
@@ -748,11 +752,13 @@ static void cx231xx_initialize(struct i2c_client *client)
        INIT_WORK(&state->fw_work, cx25840_work_handler);
        init_waitqueue_head(&state->fw_wait);
        q = create_singlethread_workqueue("cx25840_fw");
-       prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
-       queue_work(q, &state->fw_work);
-       schedule();
-       finish_wait(&state->fw_wait, &wait);
-       destroy_workqueue(q);
+       if (q) {
+               prepare_to_wait(&state->fw_wait, &wait, TASK_UNINTERRUPTIBLE);
+               queue_work(q, &state->fw_work);
+               schedule();
+               finish_wait(&state->fw_wait, &wait);
+               destroy_workqueue(q);
+       }
 
        cx25840_std_setup(client);