forked from Minki/linux
mac80211: mesh: fix call_rcu() usage
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.
Cc: stable@vger.kernel.org
Fixes: eb2b9311fd
("mac80211: mesh path table implementation")
Reported-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
parent
45bb780a21
commit
c2e703a552
@ -779,10 +779,8 @@ void mesh_plink_broken(struct sta_info *sta)
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static void mesh_path_node_reclaim(struct rcu_head *rp)
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{
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struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
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struct ieee80211_sub_if_data *sdata = node->mpath->sdata;
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del_timer_sync(&node->mpath->timer);
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atomic_dec(&sdata->u.mesh.mpaths);
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kfree(node->mpath);
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kfree(node);
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}
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@ -790,8 +788,9 @@ static void mesh_path_node_reclaim(struct rcu_head *rp)
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/* needs to be called with the corresponding hashwlock taken */
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static void __mesh_path_del(struct mesh_table *tbl, struct mpath_node *node)
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{
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struct mesh_path *mpath;
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mpath = node->mpath;
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struct mesh_path *mpath = node->mpath;
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struct ieee80211_sub_if_data *sdata = node->mpath->sdata;
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spin_lock(&mpath->state_lock);
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mpath->flags |= MESH_PATH_RESOLVING;
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if (mpath->is_gate)
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@ -799,6 +798,7 @@ static void __mesh_path_del(struct mesh_table *tbl, struct mpath_node *node)
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hlist_del_rcu(&node->list);
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call_rcu(&node->rcu, mesh_path_node_reclaim);
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spin_unlock(&mpath->state_lock);
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atomic_dec(&sdata->u.mesh.mpaths);
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atomic_dec(&tbl->entries);
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}
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