devlink_alloc() may return NULL on allocation failure, but
prestera_devlink_alloc() unconditionally calls devlink_priv() on
the returned pointer.

This leads to a NULL pointer dereference if devlink allocation fails.
Add a check for a NULL devlink pointer and return NULL early to avoid
the crash.

Fixes: 34dd1710f5a3 ("net: marvell: prestera: Add basic devlink support")
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
---
 drivers/net/ethernet/marvell/prestera/prestera_devlink.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/marvell/prestera/prestera_devlink.c b/drivers/net/ethernet/marvell/prestera/prestera_devlink.c
index 2a4c9df4eb79..e63d95c1842f 100644
--- a/drivers/net/ethernet/marvell/prestera/prestera_devlink.c
+++ b/drivers/net/ethernet/marvell/prestera/prestera_devlink.c
@@ -387,6 +387,8 @@ struct prestera_switch *prestera_devlink_alloc(struct prestera_device *dev)
 
 	dl = devlink_alloc(&prestera_dl_ops, sizeof(struct prestera_switch),
 			   dev->dev);
+	if (!dl)
+		return NULL;
 
 	return devlink_priv(dl);
 }
-- 
2.50.1