[PATCH] media: chips-media: wave5: Fix possible ERR_PTR deference

[Alper Ak <alperyasinak1@gmail.com>]

The kthread_run() function returns either a valid task_struct pointer
or ERR_PTR() on failure. The return value was not checked and in the
error cleanup path, the code verifies if dev->irq_thread is non NULL
before calling kthread_stop(). Since ERR_PTR() values are non NULL,
this would result in passing an error pointer to kthread_stop(),
causing a kernel panic.

Add proper IS_ERR() check after kthread_run(), log the error, set
dev->irq_thread to NULL and fail the probe to prevent the driver
from operating in a broken state.

Fixes: e66ff2b08e4e ("media: chips-media: wave5: Fix Null reference while testing fluster")
Signed-off-by: Alper Ak <alperyasinak1@gmail.com>
---
 drivers/media/platform/chips-media/wave5/wave5-vpu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu.c b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
index 76d57c6b636a..bebe2bd6893b 100644
--- a/drivers/media/platform/chips-media/wave5/wave5-vpu.c
+++ b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
@@ -340,6 +340,12 @@ static int wave5_vpu_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "failed to get irq resource, falling back to polling\n");
 		sema_init(&dev->irq_sem, 1);
 		dev->irq_thread = kthread_run(irq_thread, dev, "irq thread");
+		if (IS_ERR(dev->irq_thread)) {
+			dev_err(&pdev->dev, "failed to create vpu irq thread\n");
+			ret = PTR_ERR(dev->irq_thread);
+			dev->irq_thread = NULL;
+			goto err_vdi_release;
+		}
 		hrtimer_setup(&dev->hrtimer, &wave5_vpu_timer_callback, CLOCK_MONOTONIC,
 			      HRTIMER_MODE_REL_PINNED);
 		dev->worker = kthread_run_worker(0, "vpu_irq_thread");
-- 
2.43.0