linux-kernel - [034/118] wireless: regulatory: fix channel disabling race condition

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1368193181.136500812@decadent.org.uk>
Date:	Fri, 10 May 2013 14:39:41 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Johannes Berg" <johannes.berg@...el.com>
Subject: [034/118] wireless: regulatory: fix channel disabling race condition

3.2.45-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@...el.com>

commit 990de49f74e772b6db5208457b7aa712a5f4db86 upstream.

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.

Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/wireless/reg.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -853,7 +853,7 @@ static void handle_channel(struct wiphy
 			return;

 		REG_DBG_PRINT("Disabling freq %d MHz\n", chan->center_freq);
-		chan->flags = IEEE80211_CHAN_DISABLED;
+		chan->flags |= IEEE80211_CHAN_DISABLED;
 		return;
 	}

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/