[LEDE-DEV] [PATCH 4/5 netifd] Prevent premature device free in interface_claim_device

[Hans Dedecker]

interface_set_device_config can trigger a device free (for example
if the device is here only present in a bridge), which renders dev
invalid and leads to segfault. Add a lock to prevent this and
clean-up the code for readability.

Signed-off-by: Gino Peeters <peeters.gino at gmail.com>
Signed-off-by: Hans Dedecker <dedeckeh at gmail.com>
---
 interface.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/interface.c b/interface.c
index 0b9893c..1a31f4a 100644
--- a/interface.c
+++ b/interface.c
@@ -581,7 +581,6 @@ static void
 interface_claim_device(struct interface *iface)
 {
 	struct interface *parent;
-	struct device *dev = NULL;
 
 	if (iface->parent_iface.iface)
 		interface_remove_user(&iface->parent_iface);
@@ -592,15 +591,19 @@ interface_claim_device(struct interface *iface)
 		interface_add_user(&iface->parent_iface, parent);
 	} else if (iface->ifname &&
 		!(iface->proto_handler->flags & PROTO_FLAG_NODEV)) {
+		struct device *dev = NULL;
+
 		dev = device_get(iface->ifname, true);
-		interface_set_device_config(iface, dev);
-	} else {
-		dev = iface->ext_dev.dev;
+		if (dev) {
+			device_lock();
+			interface_set_device_config(iface, dev);
+			interface_set_main_dev(iface, dev);
+			device_unlock();
+		}
+	} else if (iface->ext_dev.dev) {
+		interface_set_main_dev(iface, iface->ext_dev.dev);
 	}
 
-	if (dev)
-		interface_set_main_dev(iface, dev);
-
 	if (iface->proto_handler->flags & PROTO_FLAG_INIT_AVAILABLE)
 		interface_set_available(iface, true);
 }
-- 
1.9.1