From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: [PATCH] nl80211: take RCU read lock when calling ieee80211_bss_get_ie() Date: Sun, 14 Jan 2018 19:03:38 +0100 Message-ID: <20180114180338.GA1569@light.dominikbrodowski.net> References: <20171222072012.GA3110@light.dominikbrodowski.net> <20171230131132.GA2624@light.dominikbrodowski.net> <20180108100403.GA4715@light.dominikbrodowski.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@intel.com Return-path: Received: from isilmar-4.linta.de ([136.243.71.142]:55274 "EHLO isilmar-4.linta.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751726AbeANSDp (ORCPT ); Sun, 14 Jan 2018 13:03:45 -0500 Content-Disposition: inline In-Reply-To: <20180108100403.GA4715@light.dominikbrodowski.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 patch fixes the regression I reported in the last couple of weeks for various v4.15-rcX revisions to netdev, where a "suspicious RCU usage" showed up in net/wireless/util.c:778. diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 2b3dbcd40e46..1eecc249fb5e 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -2618,8 +2618,10 @@ 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); + rcu_read_unlock(); if (!ssid_ie) break; if (nla_put(msg, NL80211_ATTR_SSID, ssid_ie[1], ssid_ie + 2))