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=-13.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 2A741C43603 for ; Wed, 18 Dec 2019 06:54:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0BBE2176D for ; Wed, 18 Dec 2019 06:54:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vCKxWaqe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725882AbfLRGyB (ORCPT ); Wed, 18 Dec 2019 01:54:01 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:43304 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725881AbfLRGyB (ORCPT ); Wed, 18 Dec 2019 01:54:01 -0500 Received: by mail-qk1-f194.google.com with SMTP id t129so696243qke.10 for ; Tue, 17 Dec 2019 22:54:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=GLhxFx+jYmIZ0dYYbr+qydoGkkvW1VLfq/seDNzPJWU=; b=vCKxWaqe61Gj4oUaAFoGj5KHvdRR2QDJRyHlQeJAsFyDeOPcUtrixSXVLEqSdmlhIo JadsIrHS6C5LA0kPytkBXnzg9ogSnw5zdyr/vJ5kv1MVnmDT24+EEfYZt1rQLNx0sbQ/ 0erg3Fx9aqK2u+CBtXwULMumfUpLspJD69N+Z8JgKWc09WGKr8u1pHXC/Fp7guKgz3/d gJ5PtyXP1NW1fXw1WCrS5kxQLBud8nPd5Ij4rZw/MnQgj7VDG0FM9MTo+EFXeY+Dz0nU p6BH73VrkN384uPrKqlKszGNGSw8MN+4gy3487Jg+XiUiNCdKVsNqGZFFG/QdAcxfEG/ hR6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=GLhxFx+jYmIZ0dYYbr+qydoGkkvW1VLfq/seDNzPJWU=; b=Gc7sEQAYHKFvrlGAd4rGr2LLxLQ6h5MQzT30h2W2lkwqC7HvPP2jDORtP1rsZxYrcg 8yNgHcrteP3a/9UK+MYGLXzD70vf9Zc6crxMN2VEmDE901DlMjdJbvNUFJ3UmsWLJimv eXpT1z/bMJD1zi8Gdj5afWi8ZfgxRmMpBydsvlG6a4ly9PXwAXkCSHu9YL1/wQAkqref s5kfJMF7mRexiR58SUiHgTAOKBY+xIm5z0W+MO4gsD+oZJzsGfa7FuhcfrjTT6OtnFSI YCNHk39SOLli73Nfs9Bs9uAFHiLMo/9w9tNqIZlKECkBpCjCM9Bb+lXplM58+GbHsFFr OgZw== X-Gm-Message-State: APjAAAW+uIK3rwA5YTMIbCA5ruAdwnq5OQHbZFDLVKzL+JIk8xiLV9Jj 8of6/Qd4MbHZ11p1N8+HcCtrfVUkAsiC9f5sbFeMlQ== X-Google-Smtp-Source: APXvYqybdHW/P5et8aH9D7M2aQAATxvAXQBdGqmtOGxAufJjrRSMrEuzLcDymgw9/pBO1vejyiMtVW6iYsHlskS0C2E= X-Received: by 2002:ae9:eb48:: with SMTP id b69mr950493qkg.43.1576652039963; Tue, 17 Dec 2019 22:53:59 -0800 (PST) MIME-Version: 1.0 References: <20191213093357.GB2135612@kroah.com> <201912180055.xBI0txro079201@www262.sakura.ne.jp> In-Reply-To: <201912180055.xBI0txro079201@www262.sakura.ne.jp> From: Dmitry Vyukov Date: Wed, 18 Dec 2019 07:53:48 +0100 Message-ID: Subject: Re: BUG: unable to handle kernel NULL pointer dereference in mem_serial_out To: Tetsuo Handa Cc: Greg KH , syzbot , Andy Shevchenko , asierra@xes-inc.com, ext-kimmo.rautkoski@vaisala.com, Jiri Slaby , kai heng feng , LKML , linux-serial , mika.westerberg@linux.intel.com, o.barta89@gmail.com, paulburton@kernel.org, sr@denx.de, syzkaller-bugs , yegorslists@googlemail.com Content-Type: text/plain; charset="UTF-8" Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Wed, Dec 18, 2019 at 1:56 AM Tetsuo Handa wrote: > > Hmm, this is a surprising bug. syzbot provided a C reproducer, but the definition > of "struct serial_struct" used in that reproducer is wrong. As a result, syzbot was > reporting crash caused by passing wrong arguments. ;-) We are on it: https://github.com/google/syzkaller/blob/master/sys/linux/dev_ptmx.txt.warn#L20-L25 > close_delay field used in the C reproducer is sizeof(unsigned int) bytes rather than > sizeof(unsigned short) bytes, thus fields after close_delay field are incorrectly > interpreted. > > ---------------------------------------- > #include > #include > #include > #include > #include > #include > > struct bad_serial_struct { > int type; > int line; > unsigned int port; > int irq; > int flags; > int xmit_fifo_size; > int custom_divisor; > int baud_base; > unsigned int close_delay; /* Correct type is "unsigned short". */ > char io_type; > char reserved_char[1]; > int hub6; > unsigned short closing_wait; > unsigned short closing_wait2; > unsigned char *iomem_base; > unsigned short iomem_reg_shift; > unsigned int port_high; > unsigned long iomap_base; > }; > > int main(int argc, char *argv[]) > { > struct bad_serial_struct ss = { }; > int fd = open("/dev/ttyS3", O_RDONLY); > ss.type = 0xa; > ss.line = 0x400000; > ss.port = 0x100; > ss.irq = 0; > ss.flags = 0x400000; > ss.xmit_fifo_size = 0; > ss.custom_divisor = 0; > ss.baud_base = 0x80000; > ss.close_delay = 0x200ff; > ss.io_type = 0; > ss.reserved_char[0] = 0x41; > ss.hub6 = 3; > ss.closing_wait = 0; > ss.closing_wait2 = 0x7c5; > ss.iomem_base = NULL; > ss.iomem_reg_shift = 0; > ss.port_high = 0; > ss.iomap_base = 0; > ioctl(fd, TIOCSSERIAL, &ss); > return 0; > } > ----------------------------------------