From patchwork Tue Apr 21 15:24:04 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 463211 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id A9896140213; Wed, 22 Apr 2015 01:25:22 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Yka35-0003i7-2s; Tue, 21 Apr 2015 15:25:19 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Yka1v-00031d-A3 for kernel-team@lists.ubuntu.com; Tue, 21 Apr 2015 15:24:07 +0000 Received: from av-217-129-142-138.netvisao.pt ([217.129.142.138] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1Yka1u-0007X6-GJ; Tue, 21 Apr 2015 15:24:07 +0000 From: Luis Henriques To: Johannes Berg Subject: [3.16.y-ckt stable] Patch "mac80211: fix RX A-MPDU session reorder timer deletion" has been added to staging queue Date: Tue, 21 Apr 2015 16:24:04 +0100 Message-Id: <1429629844-20376-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 3.16 Cc: kernel-team@lists.ubuntu.com X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled mac80211: fix RX A-MPDU session reorder timer deletion to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt10. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From e4687bfe62f6c7ebe14c94a4b8f6e9539c637604 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 1 Apr 2015 14:20:42 +0200 Subject: mac80211: fix RX A-MPDU session reorder timer deletion commit 788211d81bfdf9b6a547d0530f206ba6ee76b107 upstream. There's an issue with the way the RX A-MPDU reorder timer is deleted that can cause a kernel crash like this: * tid_rx is removed - call_rcu(ieee80211_free_tid_rx) * station is destroyed * reorder timer fires before ieee80211_free_tid_rx() runs, accessing the station, thus potentially crashing due to the use-after-free The station deletion is protected by synchronize_net(), but that isn't enough -- ieee80211_free_tid_rx() need not have run when that returns (it deletes the timer.) We could use rcu_barrier() instead of synchronize_net(), but that's much more expensive. Instead, to fix this, add a field tracking that the session is being deleted. In this case, the only re-arming of the timer happens with the reorder spinlock held, so make that code not rearm it if the session is being deleted and also delete the timer after setting that field. This ensures the timer cannot fire after ___ieee80211_stop_rx_ba_session() returns, which fixes the problem. Signed-off-by: Johannes Berg [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques --- net/mac80211/agg-rx.c | 8 ++++++-- net/mac80211/rx.c | 7 ++++--- net/mac80211/sta_info.h | 2 ++ 3 files changed, 12 insertions(+), 5 deletions(-) diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c index 31bf2586fb84..9608c6e65887 100644 --- a/net/mac80211/agg-rx.c +++ b/net/mac80211/agg-rx.c @@ -49,8 +49,6 @@ static void ieee80211_free_tid_rx(struct rcu_head *h) container_of(h, struct tid_ampdu_rx, rcu_head); int i; - del_timer_sync(&tid_rx->reorder_timer); - for (i = 0; i < tid_rx->buf_size; i++) dev_kfree_skb(tid_rx->reorder_buf[i]); kfree(tid_rx->reorder_buf); @@ -93,6 +91,12 @@ void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid, del_timer_sync(&tid_rx->session_timer); + /* make sure ieee80211_sta_reorder_release() doesn't re-arm the timer */ + spin_lock_bh(&tid_rx->reorder_lock); + tid_rx->removed = true; + spin_unlock_bh(&tid_rx->reorder_lock); + del_timer_sync(&tid_rx->reorder_timer); + call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx); } diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index a70f4ce4f652..07fb67803097 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -792,9 +792,10 @@ static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata, set_release_timer: - mod_timer(&tid_agg_rx->reorder_timer, - tid_agg_rx->reorder_time[j] + 1 + - HT_RX_REORDER_BUF_TIMEOUT); + if (!tid_agg_rx->removed) + mod_timer(&tid_agg_rx->reorder_timer, + tid_agg_rx->reorder_time[j] + 1 + + HT_RX_REORDER_BUF_TIMEOUT); } else { del_timer(&tid_agg_rx->reorder_timer); } diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h index 4acc5fc402fa..5a600151ba5a 100644 --- a/net/mac80211/sta_info.h +++ b/net/mac80211/sta_info.h @@ -162,6 +162,7 @@ struct tid_ampdu_tx { * @dialog_token: dialog token for aggregation session * @rcu_head: RCU head used for freeing this struct * @reorder_lock: serializes access to reorder buffer, see below. + * @removed: this session is removed (but might have been found due to RCU) * * This structure's lifetime is managed by RCU, assignments to * the array holding it must hold the aggregation mutex. @@ -185,6 +186,7 @@ struct tid_ampdu_rx { u16 buf_size; u16 timeout; u8 dialog_token; + bool removed; }; /**