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[2620:137:e000::1:20]) by mx.google.com with ESMTP id g5-20020a635205000000b0050017092042si59208pgb.383.2023.03.13.10.55.44; Mon, 13 Mar 2023 10:55:59 -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="Rq7/INmZ"; 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 S231561AbjCMRWP (ORCPT + 99 others); Mon, 13 Mar 2023 13:22:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42924 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231526AbjCMRVp (ORCPT ); Mon, 13 Mar 2023 13:21:45 -0400 Received: from m12.mail.163.com (m12.mail.163.com [220.181.12.214]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 92E9E7EA2D; Mon, 13 Mar 2023 10:20:48 -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=eLJUV 6sjqfvqr0F03Ruwnu9Zfyv3B41EL3cm8DE360Q=; b=Rq7/INmZhRuUz7zMSWFOv FpClKUpVM8om0Z91hkaERbkX7bqlunG0xfvS3YvbEzHSu/itud0cFhGYWUe46OnN FhdneKlDi+SzZYW7HCCIk3sNbxpzMjzsAQz9rA/JX2S3N9A1fxoT86KI9WtgHPi9 ztHBjLTScGPtjDGhmevdl0= Received: from leanderwang-LC2.localdomain (unknown [111.206.145.21]) by zwqz-smtp-mta-g4-3 (Coremail) with SMTP id _____wD3UUyAVg9kwRISAA--.11282S2; Tue, 14 Mar 2023 00:59:45 +0800 (CST) From: Zheng Wang To: ericvh@gmail.com Cc: michal.swiatkowski@linux.intel.com, 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 v3] 9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition Date: Tue, 14 Mar 2023 00:59:41 +0800 Message-Id: <20230313165941.3772964-1-zyytlz.wz@163.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CM-TRANSID: _____wD3UUyAVg9kwRISAA--.11282S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7tF15Cw48JFy5Kr1kWF4DJwb_yoW8Xw43pa naka15CFy8AF10yFsYy3WxJ3WFkw48Gr1Iga12kw4fJr98Zry8XFZ5t34Yga4UArs0qF4r Cw1jgFWDGFWDA3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0zE2YLtUUUUU= X-Originating-IP: [111.206.145.21] X-CM-SenderInfo: h2113zf2oz6qqrwthudrp/1tbiXRQxU1WBo5PgAwABst X-Spam-Status: No, score=-0.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_MSPIKE_H2, RCVD_IN_VALIDITY_RPBL,SPF_HELO_NONE,SPF_PASS autolearn=no 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?1760272801419517484?= X-GMAIL-MSGID: =?utf-8?q?1760276155667260393?= 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") Reviewed-by: Michal Swiatkowski Signed-off-by: Zheng Wang --- v3: - remove unnecessary comment and move definition to the for loop suggested by Michal Swiatkowski v2: - fix type error of ring found by kernel test robot --- net/9p/trans_xen.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index c64050e839ac..df467ffb52d0 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -280,6 +280,10 @@ static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) write_unlock(&xen_9pfs_lock); for (i = 0; i < priv->num_rings; i++) { + struct xen_9pfs_dataring *ring = &priv->rings[i]; + + cancel_work_sync(&ring->work); + if (!priv->rings[i].intf) break; if (priv->rings[i].irq > 0)