Fix race in regulatory code (rhbz 919176)

kernel.spec

@@ -745,6 +745,9 @@ Patch23006: fix-child-thread-introspection.patch
 #rhbz 928024
 Patch23008: forcedeth-dma-error-check.patch
 
+#rhbz 919176
+Patch25010: wireless-regulatory-fix-channel-disabling-race-condition.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1440,6 +1443,9 @@ ApplyPatch fix-child-thread-introspection.patch
 #rhbz 928024
 ApplyPatch forcedeth-dma-error-check.patch
 
+#rhbz 919176
+ApplyPatch wireless-regulatory-fix-channel-disabling-race-condition.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2273,6 +2279,9 @@ fi
 #                 ||----w |
 #                 ||     ||
 %changelog
+* Tue Apr 16 2013 Josh Boyer <jwboyer@redhat.com>
+- Fix race in regulatory code (rhbz 919176)
+
 * Mon Apr 15 2013 Josh Boyer <jwboyer@redhat.com>
 - Fix debug patches to build on s390x/ppc
 

wireless-regulatory-fix-channel-disabling-race-condition.patch

@@ -0,0 +1,40 @@
+From: Johannes Berg <johannes.berg@intel.com>
+
+When a full scan 2.4 and 5 GHz scan is scheduled, but then the 2.4 GHz
+part of the scan disables a 5.2 GHz channel due to, e.g. receiving
+country or frequency information, that 5.2 GHz channel might already
+be in the list of channels to scan next. Then, when the driver checks
+if it should do a passive scan, that will return false and attempt an
+active scan. This is not only wrong but can also lead to the iwlwifi
+device firmware crashing since it checks regulatory as well.
+
+Fix this by not setting the channel flags to just disabled but rather
+OR'ing in the disabled flag. That way, even if the race happens, the
+channel will be scanned passively which is still (mostly) correct.
+
+Cc: stable@vger.kernel.org
+Signed-off-by: Johannes Berg <johannes.berg@intel.com>
+---
+ net/wireless/reg.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/net/wireless/reg.c b/net/wireless/reg.c
+index 93ab840..507c28e 100644
+--- a/net/wireless/reg.c
++++ b/net/wireless/reg.c
+@@ -855,7 +855,7 @@ static void handle_channel(struct wiphy *wiphy,
+ 			return;
+ 
+ 		REG_DBG_PRINT("Disabling freq %d MHz\n", chan->center_freq);
+-		chan->flags = IEEE80211_CHAN_DISABLED;
++		chan->flags |= IEEE80211_CHAN_DISABLED;
+ 		return;
+ 	}
+ 
+-- 
+1.8.0
+
+--
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