From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: [PATCH v2] nl80211: take RCU read lock when calling ieee80211_bss_get_ie() Date: Sun, 14 Jan 2018 23:22:55 +0100 Message-ID: <20180114222255.GA9036@light.dominikbrodowski.net> References: <20171222072012.GA3110@light.dominikbrodowski.net> <20171230131132.GA2624@light.dominikbrodowski.net> <20180108100403.GA4715@light.dominikbrodowski.net> <20180114180338.GA1569@light.dominikbrodowski.net> <1515967102.26804.31.camel@sipsolutions.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: regressions@leemhuis.info, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org To: Johannes Berg Return-path: Received: from isilmar-4.linta.de ([136.243.71.142]:40310 "EHLO isilmar-4.linta.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752124AbeANWXW (ORCPT ); Sun, 14 Jan 2018 17:23:22 -0500 Content-Disposition: inline In-Reply-To: <1515967102.26804.31.camel@sipsolutions.net> Sender: netdev-owner@vger.kernel.org List-ID: As ieee80211_bss_get_ie() derefences an RCU, it needs to be called with rcu_read_lock held. Fixes: 44905265bc15 ("nl80211: don't expose wdev->ssid for most interfaces") Signed-off-by: Dominik Brodowski --- > This uses the ssid_ie, so that doesn't really seem right? The > protection should extend beyond the usage. Indeed -- I had misread the code and hadn't thought of ssid_ie also needing the protection during its lifetime. So here's a new version 2 -- which I will only be able to test tomorrow, though... Thanks, Dominik diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 2b3dbcd40e46..b53bd8db7974 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -2618,12 +2618,15 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag const u8 *ssid_ie; if (!wdev->current_bss) break; + rcu_read_lock(); ssid_ie = ieee80211_bss_get_ie(&wdev->current_bss->pub, WLAN_EID_SSID); if (!ssid_ie) - break; + goto nla_rcu_unlock; if (nla_put(msg, NL80211_ATTR_SSID, ssid_ie[1], ssid_ie + 2)) - goto nla_put_failure_locked; + goto nla_put_failure_rcu_locked; + nla_rcu_unlock: + rcu_read_unlock(); break; } default: @@ -2635,6 +2638,8 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag genlmsg_end(msg, hdr); return 0; + nla_put_failure_rcu_locked: + rcu_read_unlock(); nla_put_failure_locked: wdev_unlock(wdev); nla_put_failure: