From patchwork Mon May 30 14:40:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Duoming Zhou X-Patchwork-Id: 12864716 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94259C433FE for ; Mon, 30 May 2022 15:36:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240856AbiE3Pf6 (ORCPT ); Mon, 30 May 2022 11:35:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242709AbiE3PfW (ORCPT ); Mon, 30 May 2022 11:35:22 -0400 Received: from zg8tmtyylji0my4xnjqumte4.icoremail.net (zg8tmtyylji0my4xnjqumte4.icoremail.net [162.243.164.118]) by lindbergh.monkeyblade.net (Postfix) with SMTP id 90983996B7; Mon, 30 May 2022 07:41:40 -0700 (PDT) Received: from ubuntu.localdomain (unknown [106.117.80.109]) by mail-app2 (Coremail) with SMTP id by_KCgDHeAh415Rir1sMAQ--.3918S2; Mon, 30 May 2022 22:41:08 +0800 (CST) From: Duoming Zhou To: linux-hams@vger.kernel.org Cc: jreuter@yaina.de, ralf@linux-mips.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, thomas@osterried.de, Duoming Zhou Subject: [PATCH v4] ax25: Fix ax25 session cleanup problems Date: Mon, 30 May 2022 22:40:56 +0800 Message-Id: <20220530144056.100002-1-duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: by_KCgDHeAh415Rir1sMAQ--.3918S2 X-Coremail-Antispam: 1UD129KBjvJXoWxtF45ZFWxZry7XFWfXry7KFg_yoWxGw47pF W7Ka1fJrZrXr4rCw4rWFWkWF18uw4qq3yUGr1UuFnakw13G3s8JF1ktFWjqFW3GFWfJF1D Z34UWan8Ar4kuFJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvC14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2 Y2ka0xkIwI1lc2xSY4AK67AK6ry5MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r 1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CE b7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0x vE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAI cVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2Kf nxnUUI43ZEXa7VUbkR65UUUUU== X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAg4GAVZdtZ9W2gAIsu Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org There are session cleanup problems in ax25_release() and ax25_disconnect(). If we setup a session and then disconnect, the disconnected session is still in "LISTENING" state that is shown below. Active AX.25 sockets Dest Source Device State Vr/Vs Send-Q Recv-Q DL9SAU-4 DL9SAU-3 ??? LISTENING 000/000 0 0 DL9SAU-3 DL9SAU-4 ??? LISTENING 000/000 0 0 The first reason is caused by del_timer_sync() in ax25_release(). The timers of ax25 are used for correct session cleanup. If we use ax25_release() to close ax25 sessions and ax25_dev is not null, the del_timer_sync() functions in ax25_release() will execute. As a result, the sessions could not be cleaned up correctly, because the timers have stopped. In order to solve this problem, this patch adds a device_up flag in ax25_dev in order to judge whether the device is up. If there are sessions to be cleaned up, the del_timer_sync() in ax25_release() will not execute. What's more, we add ax25_cb_del() in ax25_kill_by_device(), because the timers have been stopped and there are no functions that could delete ax25_cb if we do not call ax25_release(). Finally, we reorder the position of ax25_list_lock in ax25_cb_del() in order to synchronize among different functions that call ax25_cb_del(). The second reason is caused by improper check in ax25_disconnect(). The incoming ax25 sessions which ax25->sk is null will close heartbeat timer, because the check "if(!ax25->sk || ..)" is satisfied. As a result, the session could not be cleaned up properly. In order to solve this problem, this patch changes "||" to "&&" in ax25_disconnect(). What`s more, the ax25_disconnect() may be called twice, which is not necessary. For example, ax25_kill_by_device() calls ax25_disconnect() and sets ax25->state to AX25_STATE_0, but ax25_release() calls ax25_disconnect() again. In order to solve this problem, this patch add a check in ax25_release(). If the flag of ax25->sk equals to SOCK_DEAD, the ax25_disconnect() in ax25_release() should not be executed. Fixes: 82e31755e55f ("ax25: Fix UAF bugs in ax25 timers") Fixes: 8a367e74c012 ("ax25: Fix segfault after sock connection timeout") Reported-and-tested-by: Thomas Osterried Signed-off-by: Duoming Zhou --- Changes in v4: - Fix session cleanup problem in ax25_disconnect(). - Fix ax25_disconnect() may be called twice problem. include/net/ax25.h | 1 + net/ax25/af_ax25.c | 27 +++++++++++++++++---------- net/ax25/ax25_dev.c | 1 + net/ax25/ax25_subr.c | 2 +- 4 files changed, 20 insertions(+), 11 deletions(-) diff --git a/include/net/ax25.h b/include/net/ax25.h index 0f9790c455b..a427a05672e 100644 --- a/include/net/ax25.h +++ b/include/net/ax25.h @@ -228,6 +228,7 @@ typedef struct ax25_dev { ax25_dama_info dama; #endif refcount_t refcount; + bool device_up; } ax25_dev; typedef struct ax25_cb { diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 363d47f9453..289f355e185 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -62,12 +62,12 @@ static void ax25_free_sock(struct sock *sk) */ static void ax25_cb_del(ax25_cb *ax25) { + spin_lock_bh(&ax25_list_lock); if (!hlist_unhashed(&ax25->ax25_node)) { - spin_lock_bh(&ax25_list_lock); hlist_del_init(&ax25->ax25_node); - spin_unlock_bh(&ax25_list_lock); ax25_cb_put(ax25); } + spin_unlock_bh(&ax25_list_lock); } /* @@ -81,6 +81,7 @@ static void ax25_kill_by_device(struct net_device *dev) if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) return; + ax25_dev->device_up = false; spin_lock_bh(&ax25_list_lock); again: @@ -91,6 +92,7 @@ static void ax25_kill_by_device(struct net_device *dev) spin_unlock_bh(&ax25_list_lock); ax25_disconnect(s, ENETUNREACH); s->ax25_dev = NULL; + ax25_cb_del(s); spin_lock_bh(&ax25_list_lock); goto again; } @@ -103,6 +105,7 @@ static void ax25_kill_by_device(struct net_device *dev) dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); ax25_dev_put(ax25_dev); } + ax25_cb_del(s); release_sock(sk); spin_lock_bh(&ax25_list_lock); sock_put(sk); @@ -995,9 +998,11 @@ static int ax25_release(struct socket *sock) if (sk->sk_type == SOCK_SEQPACKET) { switch (ax25->state) { case AX25_STATE_0: - release_sock(sk); - ax25_disconnect(ax25, 0); - lock_sock(sk); + if (!sock_flag(ax25->sk, SOCK_DEAD)) { + release_sock(sk); + ax25_disconnect(ax25, 0); + lock_sock(sk); + } ax25_destroy_socket(ax25); break; @@ -1053,11 +1058,13 @@ static int ax25_release(struct socket *sock) ax25_destroy_socket(ax25); } if (ax25_dev) { - del_timer_sync(&ax25->timer); - del_timer_sync(&ax25->t1timer); - del_timer_sync(&ax25->t2timer); - del_timer_sync(&ax25->t3timer); - del_timer_sync(&ax25->idletimer); + if (!ax25_dev->device_up) { + del_timer_sync(&ax25->timer); + del_timer_sync(&ax25->t1timer); + del_timer_sync(&ax25->t2timer); + del_timer_sync(&ax25->t3timer); + del_timer_sync(&ax25->idletimer); + } dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); ax25_dev_put(ax25_dev); } diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c index d2a244e1c26..5451be15e07 100644 --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -62,6 +62,7 @@ void ax25_dev_device_up(struct net_device *dev) ax25_dev->dev = dev; dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC); ax25_dev->forward = NULL; + ax25_dev->device_up = true; ax25_dev->values[AX25_VALUES_IPDEFMODE] = AX25_DEF_IPDEFMODE; ax25_dev->values[AX25_VALUES_AXDEFMODE] = AX25_DEF_AXDEFMODE; diff --git a/net/ax25/ax25_subr.c b/net/ax25/ax25_subr.c index 3a476e4f6cd..227c2b09c52 100644 --- a/net/ax25/ax25_subr.c +++ b/net/ax25/ax25_subr.c @@ -268,7 +268,7 @@ void ax25_disconnect(ax25_cb *ax25, int reason) del_timer_sync(&ax25->t3timer); del_timer_sync(&ax25->idletimer); } else { - if (!ax25->sk || !sock_flag(ax25->sk, SOCK_DESTROY)) + if (!ax25->sk && !sock_flag(ax25->sk, SOCK_DESTROY)) ax25_stop_heartbeat(ax25); ax25_stop_t1timer(ax25); ax25_stop_t2timer(ax25);