Paul E. McKenney
2013-Oct-09 21:29 UTC
[Bridge] [PATCH v2 tip/core/rcu 04/13] wireless: Apply rcu_access_pointer() to avoid sparse false positive
From: "Paul E. McKenney" <paulmck at linux.vnet.ibm.com>
The sparse checking for rcu_assign_pointer() was recently upgraded
to reject non-__kernel address spaces. This also rejects __rcu,
which is almost always the right thing to do. However, the uses in
cfg80211_combine_bsses() and cfg80211_bss_update() are legitimate:
They are assigning a pointer to an element from an RCU-protected list,
and all elements of this list are already visible to caller.
This commit therefore silences these false positives by laundering the
pointers using rcu_access_pointer() as suggested by Josh Triplett.
Reported-by: kbuild test robot <fengguang.wu at intel.com>
Signed-off-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Cc: Stephen Hemminger <stephen at networkplumber.org>
Cc: "David S. Miller" <davem at davemloft.net>
Cc: bridge at lists.linux-foundation.org
Cc: netdev at vger.kernel.org
---
net/wireless/scan.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index eeb71480f1af..edde117c1863 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -671,7 +671,7 @@ static bool cfg80211_combine_bsses(struct
cfg80211_registered_device *dev,
bss->pub.hidden_beacon_bss = &new->pub;
new->refcount += bss->refcount;
rcu_assign_pointer(bss->pub.beacon_ies,
- new->pub.beacon_ies);
+ rcu_access_pointer(new->pub.beacon_ies));
}
return true;
@@ -706,10 +706,10 @@ cfg80211_bss_update(struct cfg80211_registered_device
*dev,
old = rcu_access_pointer(found->pub.proberesp_ies);
rcu_assign_pointer(found->pub.proberesp_ies,
- tmp->pub.proberesp_ies);
+ rcu_access_pointer(tmp->pub.proberesp_ies));
/* Override possible earlier Beacon frame IEs */
rcu_assign_pointer(found->pub.ies,
- tmp->pub.proberesp_ies);
+ rcu_access_pointer(tmp->pub.proberesp_ies));
if (old)
kfree_rcu((struct cfg80211_bss_ies *)old,
rcu_head);
@@ -740,12 +740,12 @@ cfg80211_bss_update(struct cfg80211_registered_device
*dev,
old = rcu_access_pointer(found->pub.beacon_ies);
rcu_assign_pointer(found->pub.beacon_ies,
- tmp->pub.beacon_ies);
+ rcu_access_pointer(tmp->pub.beacon_ies));
/* Override IEs if they were from a beacon before */
if (old == rcu_access_pointer(found->pub.ies))
rcu_assign_pointer(found->pub.ies,
- tmp->pub.beacon_ies);
+ rcu_access_pointer(tmp->pub.beacon_ies));
/* Assign beacon IEs to all sub entries */
list_for_each_entry(bss, &found->hidden_list,
@@ -756,7 +756,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
WARN_ON(ies != old);
rcu_assign_pointer(bss->pub.beacon_ies,
- tmp->pub.beacon_ies);
+ rcu_access_pointer(tmp->pub.beacon_ies));
}
if (old)
@@ -804,7 +804,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
&hidden->hidden_list);
hidden->refcount++;
rcu_assign_pointer(new->pub.beacon_ies,
- hidden->pub.beacon_ies);
+ rcu_access_pointer(hidden->pub.beacon_ies));
}
} else {
/*
--
1.8.1.5