net: dev_close() should check IFF_UP

Commit 443457242beb (factorize sync-rcu call in
unregister_netdevice_many) mistakenly removed one test from dev_close()

Following actions trigger a BUG :

modprobe bonding
modprobe dummy
ifconfig bond0 up
ifenslave bond0 dummy0
rmmod dummy

dev_close() must not close a non IFF_UP device.

With help from Frank Blaschka and Einar EL Lueck

Reported-by: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Reported-by: Einar EL Lueck <ELELUECK@de.ibm.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 4 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 856b6ee9a1d5..92009440d28b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1284,11 +1284,13 @@ static int dev_close_many(struct list_head *head)
  */
 int dev_close(struct net_device *dev)
 {
-        LIST_HEAD(single);
+        if (dev->flags & IFF_UP) {
+                LIST_HEAD(single);
 
-        list_add(&dev->unreg_list, &single);
-        dev_close_many(&single);
-        list_del(&single);
+                list_add(&dev->unreg_list, &single);
+                dev_close_many(&single);
+                list_del(&single);
+        }
         return 0;
 }
 EXPORT_SYMBOL(dev_close);