ifmsh->csa was being dereferenced without the RCU read
lock held.
fixes the following warning:
[ 74.930435] =============================
[ 74.932066] WARNING: suspicious RCU usage
[ 74.933671] 4.20.13 #5 Tainted: G W
[ 74.935804] -----------------------------
[ 74.937427] net/mac80211/mesh.c:1218 suspicious rcu_dereference_check() usage!
[ 74.940473] other info that might help us debug this:
[ 74.943654] rcu_scheduler_active = 2, debug_locks = 1
[ 74.946311] 5 locks held by kworker/u8:3/107:
[ 74.948087] #0: 000000007623c1f0 ((wq_completion)"%s"wiphy_name(local->hw.wiphy)){+.+.}, at: process_one_work+0x1a2/0x610
[ 74.952464] #1: 00000000077b4215 ((work_completion)(&sdata->csa_finalize_work)){+.+.}, at: process_one_work+0x1a2/0x610
[ 74.957228] #2: 00000000e02b12da (&wdev->mtx){+.+.}, at: ieee80211_csa_finalize_work+0x2f/0x90
[ 74.959870] #3: 00000000e6855095 (&local->mtx){+.+.}, at: ieee80211_csa_finalize_work+0x47/0x90
[ 74.962937] #4: 00000000bb5e3bca (&local->chanctx_mtx){+.+.}, at: ieee80211_csa_finalize_work+0x51/0x90
Signed-off-by: Thomas Pedersen <thomas@xxxxxxxx>
---
net/mac80211/mesh.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 766e5e5..70aeb34 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -1220,10 +1220,12 @@ int ieee80211_mesh_finish_csa(struct ieee80211_sub_if_data *sdata)
ifmsh->chsw_ttl = 0;
/* Remove the CSA and MCSP elements from the beacon */
+ rcu_read_lock();
tmp_csa_settings = rcu_dereference(ifmsh->csa);
RCU_INIT_POINTER(ifmsh->csa, NULL);
if (tmp_csa_settings)
kfree_rcu(tmp_csa_settings, rcu_head);
+ rcu_read_unlock();
ret = ieee80211_mesh_rebuild_beacon(sdata);
if (ret)
return -EINVAL;
--
2.7.4
