[PATCH] soundwire: intel_init: test link->cdns

[Bard Liao]

intel_link_probe() could return error and dev_get_drvdata() will return
null in such case. So we have to test link->cdns after
link->cdns = dev_get_drvdata(&ldev->auxdev.dev);
Otherwise, we will meet the "kernel NULL pointer dereference" error.

Signed-off-by: Bard Liao <yung-chuan.liao at linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Reviewed-by: Rander Wang <rander.wang at intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 drivers/soundwire/intel_init.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c
index 5b32a2ffd376..5ef5bd0defab 100644
--- a/drivers/soundwire/intel_init.c
+++ b/drivers/soundwire/intel_init.c
@@ -250,6 +250,15 @@ static struct sdw_intel_ctx
 		link = &ldev->link_res;
 		link->cdns = dev_get_drvdata(&ldev->auxdev.dev);
 
+		if (!link->cdns) {
+			dev_err(&adev->dev, "failed to get link->cdns\n");
+			/*
+			 * 1 will be subtracted from i in the err label, but we need to call
+			 * intel_link_dev_unregister for this ldev, so plus 1 now
+			 */
+			i++;
+			goto err;
+		}
 		list_add_tail(&link->list, &ctx->link_list);
 		bus = &link->cdns->bus;
 		/* Calculate number of slaves */
-- 
2.17.1