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=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 546F9C433DF for ; Mon, 10 Aug 2020 11:06:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2FC662073A for ; Mon, 10 Aug 2020 11:06:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597057581; bh=iCudXyjdYzGdwBeDT9k0njKXIiJW45q0BJa7WH0s4Dc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=omeQyWG2uzGKpEd8DUxsJGc1ECqPcnReT+DsljEYCvLRP8NHPBG+4kWotHBg6ezjq 82eucY5LRvYPmIh9Q4ccIzZM9L7ilNP2aFFcMxcr58I0fKI/PETt8l9NQukh9YK/7w 2eNrgah8l6ytta+8HRQ3GhHQHDA6I9BDTHfh/NoA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726596AbgHJLGQ (ORCPT ); Mon, 10 Aug 2020 07:06:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:43198 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726368AbgHJLGM (ORCPT ); Mon, 10 Aug 2020 07:06:12 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C15220729; Mon, 10 Aug 2020 11:06:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597057565; bh=iCudXyjdYzGdwBeDT9k0njKXIiJW45q0BJa7WH0s4Dc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Z6eT13jgvH1KgFLo4PP1uO1yglBPMk1iFWkVhMmoCHpwDj4kJa4iMoRswlSbq2sWc w1/S1CEcrlWQeDm71kCfbONmR0+vnJRdeekSbtJuk3aVYyX2PMBiLI6WDLVt36BaqQ GKyQkCR0P03BgDtUGLKl+Qr1ish6QyANqXtgnqac= Date: Mon, 10 Aug 2020 13:06:16 +0200 From: Greg KH To: Dmitry Vyukov Cc: syzbot , Andrey Konovalov , balbi@kernel.org, Dan Carpenter , Alexander Potapenko , LKML , USB list , syzkaller-bugs Subject: Re: KMSAN: kernel-infoleak in raw_ioctl Message-ID: <20200810110616.GA2415197@kroah.com> References: <000000000000ce85c405ac744ff6@google.com> <20200810074706.GD1529187@kroah.com> <20200810090833.GA2271719@kroah.com> <20200810091538.GA2273701@kroah.com> <20200810095754.GA2404978@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, Aug 10, 2020 at 12:21:49PM +0200, Dmitry Vyukov wrote: > On Mon, Aug 10, 2020 at 11:57 AM Greg KH wrote: > > > > On Mon, Aug 10, 2020 at 11:15:38AM +0200, Greg KH wrote: > > > On Mon, Aug 10, 2020 at 11:08:33AM +0200, Greg KH wrote: > > > > On Mon, Aug 10, 2020 at 11:00:07AM +0200, Dmitry Vyukov wrote: > > > > > On Mon, Aug 10, 2020 at 9:46 AM Greg KH wrote: > > > > > > > > > > > > On Sun, Aug 09, 2020 at 09:27:18AM -0700, syzbot wrote: > > > > > > > Hello, > > > > > > > > > > > > > > syzbot found the following issue on: > > > > > > > > > > > > > > HEAD commit: ce8056d1 wip: changed copy_from_user where instrumented > > > > > > > git tree: https://github.com/google/kmsan.git master > > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=141eb8b2900000 > > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=3afe005fb99591f > > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=a7e220df5a81d1ab400e > > > > > > > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > > > > > > > userspace arch: i386 > > > > > > > > > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > > > > > > > The irony of a kernel module written for syzbot testing, causing syzbot > > > > > > reports.... > > > > > > > > > > The raw gadget and KCOV are also kernel code and subject to all the > > > > > same rules as any other kernel code from syzkaller point of view. > > > > > > > > > > But I think the root cause of this bug is the origin of the uninitialized-ness: > > > > > > > > > > Local variable ----buf.i@asix_get_phy_addr created at: > > > > > asix_read_cmd drivers/net/usb/asix_common.c:312 [inline] > > > > > asix_read_phy_addr drivers/net/usb/asix_common.c:295 [inline] > > > > > asix_get_phy_addr+0x4d/0x290 drivers/net/usb/asix_common.c:314 > > > > > asix_read_cmd drivers/net/usb/asix_common.c:312 [inline] > > > > > asix_read_phy_addr drivers/net/usb/asix_common.c:295 [inline] > > > > > asix_get_phy_addr+0x4d/0x290 drivers/net/usb/asix_common.c:314 > > > > > > > > read buffers sent to USB hardware are ment to be filled in by the > > > > hardware with the data received from it, we do not zero-out those > > > > buffers before passing the pointer there. > > > > > > > > Perhaps with testing frameworks like the raw usb controller, that might > > > > cause a number of false-positives to happen? > > > > > > Ah, wait, that buffer is coming from the stack, which isn't allowed in > > > the first place :( > > > > > > So that should be changed anyway to a dynamic allocation, I'll go write > > > up a patch... > > > > Nope, my fault, the data is not coming from the stack, so all is good. > > My reading of the code is that asix_read_cmd returns the number of > bytes actually read, which may be less than requested. > This happens in __usbnet_read_cmd: > https://elixir.bootlin.com/linux/latest/source/drivers/net/usb/usbnet.c#L2002 > So this code in asix_read_phy_addr will need produce an uninit value > for result if <2 bytes read: > > u8 buf[2]; > int ret = asix_read_cmd(dev, AX_CMD_READ_PHY_ID, 0, 0, 2, buf, 0); > if (ret < 0) > netdev_err(dev->net, "Error reading PHYID register: %02x\n", ret); > ret = buf[offset]; > return ret; > > And it looks like all of 13 uses of asix_read_cmd in > drivers/net/usb/asix_common.c are subject to this bug as well. Ah, yeah, and no one checks error values either, there's even a TODO statement in the driver about that :( Good catch, I'll point some interns at this and see if they can fix it up, thanks! greg k-h