@@ -779,10 +779,8 @@ void mesh_plink_broken(struct sta_info *sta)
static void mesh_path_node_reclaim(struct rcu_head *rp)
{
struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
- struct ieee80211_sub_if_data *sdata = node->mpath->sdata;
del_timer_sync(&node->mpath->timer);
- atomic_dec(&sdata->u.mesh.mpaths);
kfree(node->mpath);
kfree(node);
}
@@ -790,8 +788,9 @@ static void mesh_path_node_reclaim(struct rcu_head *rp)
/* needs to be called with the corresponding hashwlock taken */
static void __mesh_path_del(struct mesh_table *tbl, struct mpath_node *node)
{
- struct mesh_path *mpath;
- mpath = node->mpath;
+ struct mesh_path *mpath = node->mpath;
+ struct ieee80211_sub_if_data *sdata = node->mpath->sdata;
+
spin_lock(&mpath->state_lock);
mpath->flags |= MESH_PATH_RESOLVING;
if (mpath->is_gate)
@@ -799,6 +798,7 @@ static void __mesh_path_del(struct mesh_table *tbl, struct mpath_node *node)
hlist_del_rcu(&node->list);
call_rcu(&node->rcu, mesh_path_node_reclaim);
spin_unlock(&mpath->state_lock);
+ atomic_dec(&sdata->u.mesh.mpaths);
atomic_dec(&tbl->entries);
}
This is a note to let you know that I have just added a patch titled mac80211: mesh: fix call_rcu() usage to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt2. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 8d00e98edfd2e2d9bb1b1b7c9eaa7c2ad23b737a Mon Sep 17 00:00:00 2001 From: Johannes Berg <johannes.berg@intel.com> Date: Tue, 17 Nov 2015 14:25:21 +0100 Subject: mac80211: mesh: fix call_rcu() usage commit c2e703a55245bfff3db53b1f7cbe59f1ee8a4339 upstream. When using call_rcu(), the called function may be delayed quite significantly, and without a matching rcu_barrier() there's no way to be sure it has finished. Therefore, global state that could be gone/freed/reused should never be touched in the callback. Fix this in mesh by moving the atomic_dec() into the caller; that's not really a problem since we already unlinked the path and it will be destroyed anyway. This fixes a crash Jouni observed when running certain tests in a certain order, in which the mesh interface was torn down, the memory reused for a function pointer (work struct) and running that then crashed since the pointer had been decremented by 1, resulting in an invalid instruction byte stream. Fixes: eb2b9311fd00 ("mac80211: mesh path table implementation") Reported-by: Jouni Malinen <j@w1.fi> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/mac80211/mesh_pathtbl.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) -- 1.9.1