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[2620:137:e000::1:20]) by mx.google.com with ESMTP id r5-20020a17090b050500b002340f36b545si5402931pjz.18.2023.03.12.21.37.23; Sun, 12 Mar 2023 21:37:38 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@163.com header.s=s110527 header.b="jxU/5wgc"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=163.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229872AbjCMEPH (ORCPT + 99 others); Mon, 13 Mar 2023 00:15:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229656AbjCMEPE (ORCPT ); Mon, 13 Mar 2023 00:15:04 -0400 Received: from m12.mail.163.com (m12.mail.163.com [220.181.12.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C12152886E; Sun, 12 Mar 2023 21:15:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=SHitx /p2v515lWIUtrn7VLSosh3Eis87AfBcSEwzhzA=; b=jxU/5wgcfYNdDyK7u6Hjc DjkHb77etGnELIsNQN/ri/2VB+L9s/MYXYheXz0Ie/NKcr0oPNGpYrCMCrYdSea0 eK9QeazJYKHM0Ig3giywQfJpnz36lEWQR2jw08WBNSaWKG2YaWNnlLzlPGeR+lLX FYeMbjn3pEWORK8silVnt8= Received: from leanderwang-LC2.localdomain (unknown [111.206.145.21]) by zwqz-smtp-mta-g4-0 (Coremail) with SMTP id _____wBXdh_Rog5kJ4YGAA--.1868S2; Mon, 13 Mar 2023 12:13:05 +0800 (CST) From: Zheng Wang To: ericvh@gmail.com Cc: lucho@ionkov.net, asmadeus@codewreck.org, linux_oss@crudebyte.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, v9fs-developer@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, hackerzheng666@gmail.com, 1395428693sheep@gmail.com, alex000young@gmail.com, Zheng Wang Subject: [PATCH net] 9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition Date: Mon, 13 Mar 2023 12:13:03 +0800 Message-Id: <20230313041303.3158458-1-zyytlz.wz@163.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CM-TRANSID: _____wBXdh_Rog5kJ4YGAA--.1868S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7tF15Cw48JFy5tr1xuF45Wrg_yoW8WF4Upa 1Skrn5AFyqya1YyFsYy3WxJ3WYkw4rGr1Iga12kw4fJr98Ary8XrZ5tr1Yg34UAr4YqF4r Gw1DXa98JFZrAw7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0ziaZXrUUUUU= X-Originating-IP: [111.206.145.21] X-CM-SenderInfo: h2113zf2oz6qqrwthudrp/1tbiXQ8xU1WBo41K9wABs2 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1760225927647844423?= X-GMAIL-MSGID: =?utf-8?q?1760225927647844423?= In xen_9pfs_front_probe, it calls xen_9pfs_front_alloc_dataring to init priv->rings and bound &ring->work with p9_xen_response. When it calls xen_9pfs_front_event_handler to handle IRQ requests, it will finally call schedule_work to start the work. When we call xen_9pfs_front_remove to remove the driver, there may be a sequence as follows: Fix it by finishing the work before cleanup in xen_9pfs_front_free. Note that, this bug is found by static analysis, which might be false positive. CPU0 CPU1 |p9_xen_response xen_9pfs_front_remove| xen_9pfs_front_free| kfree(priv) | //free priv | |p9_tag_lookup |//use priv->client Fixes: 71ebd71921e4 ("xen/9pfs: connect to the backend") Signed-off-by: Zheng Wang --- net/9p/trans_xen.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index c64050e839ac..60adb3aadd63 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -274,16 +274,21 @@ static const struct xenbus_device_id xen_9pfs_front_ids[] = { static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) { int i, j; + struct xen_9pfs_dataring *ring = NULL; write_lock(&xen_9pfs_lock); list_del(&priv->list); write_unlock(&xen_9pfs_lock); for (i = 0; i < priv->num_rings; i++) { + ring = priv->rings[i]; if (!priv->rings[i].intf) break; if (priv->rings[i].irq > 0) unbind_from_irqhandler(priv->rings[i].irq, priv->dev); + + cancel_work_sync(&ring->work); + if (priv->rings[i].data.in) { for (j = 0; j < (1 << priv->rings[i].intf->ring_order);