From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3EA4C43381 for ; Tue, 19 Feb 2019 18:56:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6997A2147C for ; Tue, 19 Feb 2019 18:56:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="J5jSTP5V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728343AbfBSS4D (ORCPT ); Tue, 19 Feb 2019 13:56:03 -0500 Received: from mail-pg1-f194.google.com ([209.85.215.194]:44615 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725875AbfBSS4C (ORCPT ); Tue, 19 Feb 2019 13:56:02 -0500 Received: by mail-pg1-f194.google.com with SMTP id y1so10536884pgk.11; Tue, 19 Feb 2019 10:56:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=xWdFlFRv4CzxDczg5CgOrkaqhJptQj2iz77qch1CTNA=; b=J5jSTP5V8Qp/mD44DZH/iqDa8KIA28fLtIjcvmY5vFkIwvOhgiB+wCoUTDsybaZ5rw HwbKx43Ov1cwsu6ZySr+Lq1RWrtBbK4xs2P/1mSInPZEFUvBsh59KJli/lOsewz5hwLE VGE2KLCir57nwtCgqTCmY264DpytD9pzl5skIq+3xbbzwvVsvOhkG2rW5V4gpu4MHHYU BbitI1PlZmzGIHsz5p9xifE6kLnmL53ziRwfkinzAxOz5Bqdvq4VddqmL1u+uy9Bqy0U f0kpNmzH+tGsHQNFcnmg6QYxXRV5iyMXlb6nDxf5swJS6abdz53NIF7JDpyt/moSZdEC jhng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=xWdFlFRv4CzxDczg5CgOrkaqhJptQj2iz77qch1CTNA=; b=r+DYgJORod3i2/lEfqA2Z8aRa/xBk13eZ5ubIF3IvQrdAYmlxlP1wSkfFiYdW2Ut/Q kqAffyx42BkQJJtc+WnlX1mf80g7Kl9SZUwTBI8ekw4BI2fGeLF5fVUt5BN0N3R5Eiow lmLtcSGfD2sSX/gOELR3oIplRcJ4HyU5o4mKeT9HtuShPS/de0EBVgdS3+nPxdEMQ/4i olrLLaY8gncB2Ec6nHTVPp1xoyy/yPO33q6HdKYz+NaWvHJbiMPcPz4ZtEbOphLraha2 DlHuU0plhjbZ/mD/tKwmu0fxUYWOwnNRH+Po77Ue2cWY6X11I+HcNJ/A+H5tov+xc8QW GNIA== X-Gm-Message-State: AHQUAuZ94YmIHb2Zv98RM4OcAr/OQ1vIXWt9Rwme1f0MSqxVaMNQrDXx nZfG0rY64fi1s6qeGiL1s5I= X-Google-Smtp-Source: AHgI3IbaoyeDCvGVYSzGPwgAgYDzWv5ya7biryNFY1ZZGRN2WnbZgGtCDNm4/hmPzMcIFjoSrQOLqg== X-Received: by 2002:a62:1d0c:: with SMTP id d12mr30915525pfd.126.1550602561138; Tue, 19 Feb 2019 10:56:01 -0800 (PST) Received: from dtor-ws ([2620:15c:202:201:3adc:b08c:7acc:b325]) by smtp.gmail.com with ESMTPSA id q18sm5533208pgv.9.2019.02.19.10.55.59 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Feb 2019 10:56:00 -0800 (PST) Date: Tue, 19 Feb 2019 10:55:58 -0800 From: Dmitry Torokhov To: Tetsuo Handa Cc: rydberg@bitmath.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Kay Sievers , syzbot Subject: Re: [PATCH] input : avoid too late kobject_uevent(KOBJ_REMOVE) call Message-ID: <20190219185558.GA210481@dtor-ws> References: <1550484563-13217-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1550484563-13217-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tetsuo, On Mon, Feb 18, 2019 at 07:09:23PM +0900, Tetsuo Handa wrote: > syzbot is hitting use-after-free bug in uinput module [1]. This is because > kobject_uevent(KOBJ_REMOVE) is called again due to commit 0f4dafc0563c6c49 > ("Kobject: auto-cleanup on final unref") after memory allocation fault > injection made kobject_uevent(KOBJ_REMOVE) from device_del() from > input_unregister_device() fail, while uinput_destroy_device() is expecting > that kobject_uevent(KOBJ_REMOVE) is not called after device_del() from > input_unregister_device() completed. > > Fix this problem by pretending as if kobject_uevent(KOBJ_REMOVE) from > device_del() from input_unregister_device() did not fail. > > [1] https://syzkaller.appspot.com/bug?id=8b17c134fe938bbddd75a45afaa9e68af43a362d > > Reported-by: syzbot > Analyzed-by: Dmitry Torokhov > Cc: Kay Sievers > Signed-off-by: Tetsuo Handa > --- > drivers/input/input.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/input/input.c b/drivers/input/input.c > index 3304aaaffe87..6df3c33ef3aa 100644 > --- a/drivers/input/input.c > +++ b/drivers/input/input.c > @@ -2032,6 +2032,19 @@ static void __input_unregister_device(struct input_dev *dev) > mutex_unlock(&input_mutex); > > device_del(&dev->dev); > + /* > + * Regarding input subsystem, we always take care of sending uevent at > + * "unregister" time, and we do not expect to have uevent sent out at > + * the final "put" time. Therefore, if we failed to send uevent at > + * "unregister" time (due to e.g. fault injection), complain it and > + * do not allow the final "put" time to send the remove uevent again. > + */ > + if (dev->dev.kobj.state_add_uevent_sent && > + !dev->dev.kobj.state_remove_uevent_sent) { > + dev->dev.kobj.state_remove_uevent_sent = 1; > + pr_warn("Failed to send remove uevent for %s\n", > + dev_name(&dev->dev)); Input has no business reaching into kobj internals. This should be solved in lib/kobject_uevent.c, not anywhere else. Thanks. -- Dmitry