media: videobuf2: Fix device reference leak in vb2_dc_alloc error path

In vb2_dc_alloc(), get_device() is called to increment the device
reference count. However, if subsequent DMA allocation fails
(vb2_dc_alloc_coherent or vb2_dc_alloc_non_coherent returns error),
the function returns without calling put_device(), causing a device
reference leak.

Add put_device() call in the error path before kfree() to properly
release the device reference acquired earlier.

Fixes: de27891f67 ("media: videobuf2: handle non-contiguous DMA allocations")
Cc: stable@vger.kernel.org
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

drivers/media/common/videobuf2/videobuf2-dma-contig.c

@@ -258,6 +258,7 @@ static void *vb2_dc_alloc(struct vb2_buffer *vb,
 
 	if (ret) {
 		dev_err(dev, "dma alloc of size %lu failed\n", size);
+		put_device(buf->dev);
 		kfree(buf);
 		return ERR_PTR(-ENOMEM);
 	}