From patchwork Thu Jul 19 20:06:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tomas Bortoli X-Patchwork-Id: 946589 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="PaMutjyi"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 41WlRS0gNVz9s4Z for ; Fri, 20 Jul 2018 06:07:16 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728087AbeGSUvq (ORCPT ); Thu, 19 Jul 2018 16:51:46 -0400 Received: from mail-lj1-f193.google.com ([209.85.208.193]:42452 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727556AbeGSUvq (ORCPT ); Thu, 19 Jul 2018 16:51:46 -0400 Received: by mail-lj1-f193.google.com with SMTP id f1-v6so7541955ljc.9; Thu, 19 Jul 2018 13:07:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=uxQ7ZVIbXjJzI3VK2/066QXTwvE33shPFfeCFLf9jAg=; b=PaMutjyiOyNjrFlxU+kx1EefLaYZt+/P+RHvufduslt6xpIosFZlLpOTnTnTVmDbsW veIitudfED1A27G6t6oPBvpaND/7oJAMbj2r9hjW/T6kTtX4Rc32kTy5kaQHfPkQG3SL szvcUvxUvEyGJYzRErqJC0pJY6RBFqXcSoewky6xu07Yl5ODftEky25JrAiEYokWmTQm 147FRVCqToiD8xDpVD2GqPkO2Ovy98Twa9k11/sacgONu2Bhjm+2DNbE4i+1dU8NvTsy Ae67sGZNVCDB8pcj2E0bN0qB5f3LGAD5U6rGNPEMwlyHkhhTZyQNqGZ9dhnBsRmbikjy njKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=uxQ7ZVIbXjJzI3VK2/066QXTwvE33shPFfeCFLf9jAg=; b=WLXbaa+Ku5pAHWWgR//dsLAcAbkIQqWqlrzauhrrwmRNL8iWxvBe0GdjjwwIXHmiTN yQIHK0GoAkQfX7bUq34AAPzyoqf/I10lPahs5uEkrfh4syCiro+n/Kl6R352zw5HfOLo JMMXqk4xfxOOcfQAToAAWthPWoIgW5Y5jz1dyu7AbZIdxIc2VKhjfa59v/uXMJuSljTi M+nppyw4mwI5+0ldqWdp4mNtSamPKYlzmFL80xbOsd67FeXR8w7c0MmQLWNSwH8yfo4I oSCDL9xuLjD6kmuMc2ASowuYkkBA2YJTPcyVSyIlC25XeFV5XB2rCDqlQ9QEsTQdzBGh zPlg== X-Gm-Message-State: AOUpUlGdISIo0+yyjtkLruP0syv2wK6PhTCgkkuQYusgHa5w6rWDWhRR Sqcv5U4WVgEeboKzeY1HGXE= X-Google-Smtp-Source: AAOMgpd5Z9aEFObvZ7s+ahXBQ8bWf4jMwyp7u5AUjseDuyku4bSm/ZDKgmGe4Y9wToJLzuNAoYAM8g== X-Received: by 2002:a2e:9d0e:: with SMTP id t14-v6mr8649997lji.112.1532030823880; Thu, 19 Jul 2018 13:07:03 -0700 (PDT) Received: from debian-tom.lan ([2001:2012:22e:1b00:f2e2:9015:9262:3fde]) by smtp.gmail.com with ESMTPSA id o11-v6sm8397ljh.34.2018.07.19.13.07.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Jul 2018 13:07:02 -0700 (PDT) From: Tomas Bortoli To: ericvh@gmail.com, rminnich@sandia.gov, lucho@ionkov.net Cc: davem@davemloft.net, v9fs-developer@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller@googlegroups.com, Tomas Bortoli Subject: [PATCH] /net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree() Date: Thu, 19 Jul 2018 22:06:07 +0200 Message-Id: <20180719200607.30286-1-tomasbortoli@gmail.com> X-Mailer: git-send-email 2.11.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The patch adds the flush in p9_mux_poll_stop() as it the function used by p9_conn_destroy(), in turn called by p9_fd_close() to stop the async polling associated with the data regarding the connection. Signed-off-by: Tomas Bortoli Reported-by: syzbot+39749ed7d9ef6dfb23f6@syzkaller.appspotmail.com --- As shown by Syzbot, it is possible to provoke a race between p9_fd_close() and p9_poll_workfn() that is called to take care of the async read/write work to do. To make sure p9_fd_close() frees "trans" when it is not used anymore, it has to explicitly call flush_scheduled_work() before the kfree(). net/9p/trans_fd.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index bf459ee0feab..76ae134c05d9 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -185,6 +185,8 @@ static void p9_mux_poll_stop(struct p9_conn *m) spin_lock_irqsave(&p9_poll_lock, flags); list_del_init(&m->poll_pending_link); spin_unlock_irqrestore(&p9_poll_lock, flags); + + flush_scheduled_work(); } /**