Hello.
On 4/26/2016 6:27 AM, Antonio Quartulli wrote:
From: Sven Eckelmann sven@narfation.org
_batadv_update_route rcu_derefences orig_ifinfo->router outside of a spinlock protected region to print some information messages to the debug log. But this pointer is not checked again when the new pointer is assigned in the spinlock protected region. Thus is can happen that the value of
Thus is can? :-)
orig_ifinfo->router changed in the meantime and thus the reference counter of the wrong router gets reduced after the spinlock protected region.
Just rcu_dereferencing the value of orig_ifinfo->router inside the spinlock protected region (which also set the new pointer) is enough to get the correct old router object.
Fixes: e1a5382f978b ("batman-adv: Make orig_node->router an rcu protected pointer") Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Marek Lindner mareklindner@neomailbox.ch Signed-off-by: Antonio Quartulli a@unstable.cc
net/batman-adv/routing.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 4dd646a52f1a..b781bf753250 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -105,6 +105,15 @@ static void _batadv_update_route(struct batadv_priv *bat_priv, neigh_node = NULL;
spin_lock_bh(&orig_node->neigh_list_lock);
- /* curr_router used earlier may not be the current orig_ifinfo->router
* anymore because it was dereferenced outside of the neigh_list_lock* protected region. After the new best neighbor has replace the current
Replaced.
[...]
MBR, Sergei