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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 8012AC32750 for ; Tue, 13 Aug 2019 12:43:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5FA9820874 for ; Tue, 13 Aug 2019 12:43:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728690AbfHMMnr (ORCPT ); Tue, 13 Aug 2019 08:43:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:38764 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726903AbfHMMno (ORCPT ); Tue, 13 Aug 2019 08:43:44 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 22B2CACD8; Tue, 13 Aug 2019 12:43:43 +0000 (UTC) Message-ID: <1565700220.7043.8.camel@suse.com> Subject: Re: KMSAN: uninit-value in smsc75xx_bind From: Oliver Neukum To: syzbot , davem@davemloft.net, glider@google.com, syzkaller-bugs@googlegroups.com, steve.glendinning@shawell.net, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, netdev@vger.kernel.org Date: Tue, 13 Aug 2019 14:43:40 +0200 In-Reply-To: <0000000000009f4316058fab3bd7@google.com> References: <0000000000009f4316058fab3bd7@google.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Freitag, den 09.08.2019, 01:48 -0700 schrieb syzbot: > Hello, > > syzbot found the following crash on: > > HEAD commit: beaab8a3 fix KASAN build > git tree: kmsan [..] > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x191/0x1f0 lib/dump_stack.c:113 > kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109 > __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294 > smsc75xx_wait_ready drivers/net/usb/smsc75xx.c:976 [inline] > smsc75xx_bind+0x541/0x12d0 drivers/net/usb/smsc75xx.c:1483 > > Local variable description: ----buf.i93@smsc75xx_bind > Variable was created at: > __smsc75xx_read_reg drivers/net/usb/smsc75xx.c:83 [inline] > smsc75xx_wait_ready drivers/net/usb/smsc75xx.c:969 [inline] > smsc75xx_bind+0x44c/0x12d0 drivers/net/usb/smsc75xx.c:1483 > usbnet_probe+0x10d3/0x3950 drivers/net/usb/usbnet.c:1722 Hi, this looks like a false positive to me. The offending code is likely this: if (size) { buf = kmalloc(size, GFP_KERNEL); if (!buf) goto out; } err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), cmd, reqtype, value, index, buf, size, USB_CTRL_GET_TIMEOUT); which uses 'buf' uninitialized. But it is used for input. What is happening here? Regards Oliver