net: dont leave active on stack LIST_HEAD

Eric W. Biderman and Michal Hocko reported various memory corruptions
that we suspected to be related to a LIST head located on stack, that
was manipulated after thread left function frame (and eventually exited,
so its stack was freed and reused).

Eric Dumazet suggested the problem was probably coming from commit
443457242beb (net: factorize
sync-rcu call in unregister_netdevice_many)

This patch fixes __dev_close() and dev_close() to properly deinit their
respective LIST_HEAD(single) before exiting.

References: https://lkml.org/lkml/2011/2/16/304
References: https://lkml.org/lkml/2011/2/14/223

Reported-by: Michal Hocko <[email protected]>
Tested-by: Michal Hocko <[email protected]>
Reported-by: Eric W. Biderman <[email protected]>
Tested-by: Eric W. Biderman <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Octavian Purdila <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

diff --git a/net/core/dev.c b/net/core/dev.c
index 8e726cb47ed78d7836471f5fa9624202cec77d55..a18c1643ea9ff8a242d68f72593dbd9ab79d23d8 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1280,10 +1280,13 @@ static int __dev_close_many(struct list_head *head)
 
 static int __dev_close(struct net_device *dev)
 {
+       int retval;
        LIST_HEAD(single);
 
        list_add(&dev->unreg_list, &single);
-       return __dev_close_many(&single);
+       retval = __dev_close_many(&single);
+       list_del(&single);
+       return retval;
 }
 
 int dev_close_many(struct list_head *head)
@@ -1325,7 +1328,7 @@ int dev_close(struct net_device *dev)
 
        list_add(&dev->unreg_list, &single);
        dev_close_many(&single);
-
+       list_del(&single);
        return 0;
 }
 EXPORT_SYMBOL(dev_close);