net: caif: clear client service pointer on teardown

From: Zhengchuan Liang <[email protected]>

caif_connect() can tear down an existing client after remote shutdown by calling caif_disconnect_client() followed by caif_free_client(). caif_free_client() releases the service layer referenced by adap_layer->dn, but leaves that pointer stale.

When the socket is later destroyed, caif_sock_destructor() calls caif_free_client() again and dereferences the freed service pointer.

Clear the client/service links before releasing the service object so repeated teardown becomes harmless.

---
 net/caif/cfsrvl.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

index 171fa32ada85c..d687fd0b4ed3a 100644
@@ -191,10 +191,20 @@ bool cfsrvl_phyid_match(struct cflayer *layer, int phyid)
 
 void caif_free_client(struct cflayer *adap_layer)
 {
+	struct cflayer *serv_layer;
 	struct cfsrvl *servl;
-	if (adap_layer == NULL || adap_layer->dn == NULL)
+
+	if (!adap_layer)
+		return;
+
+	serv_layer = adap_layer->dn;
+	if (!serv_layer)
 		return;
-	servl = container_obj(adap_layer->dn);
+
+	layer_set_dn(adap_layer, NULL);
+	layer_set_up(serv_layer, NULL);
+
+	servl = container_obj(serv_layer);
 	servl->release(&servl->layer);
 }
 EXPORT_SYMBOL(caif_free_client);

2.43.0