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=-11.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 33A3BC2D0E4 for ; Sun, 13 Sep 2020 06:21:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D059121655 for ; Sun, 13 Sep 2020 06:21:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="akCmZ/9N" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725919AbgIMGVA (ORCPT ); Sun, 13 Sep 2020 02:21:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725894AbgIMGU6 (ORCPT ); Sun, 13 Sep 2020 02:20:58 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB336C061573; Sat, 12 Sep 2020 23:20:57 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id j34so9103882pgi.7; Sat, 12 Sep 2020 23:20:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=oSqDnSurul1SEUdPfy/k5oKwDRKz1lqnIF0nSiq8EfM=; b=akCmZ/9Nebui2eLyF0x28+sRrco8/cMSEJFnvpd+8P7Jz1k7z6uC+PTbvU+vCuMe/p G6TUewI7fu6WEuZS2dD5zB34ER4PvygORHE0PlhW7oPEYdYuGTE5lmJHQAq8bm/wKDB6 q3BgXkqy1X/241LZFPFK0mhssBxffFSR6pTqPSmyoCSmbjRg7HWiem1rEEH32431q3aF X42a3cxV0QVNsh/10z7MgsxANGWQDnZlBpAcGIB2Mv4kk/Aekh2ro8Jvt2EAj7/YdDJ4 8dGcn9pAMtLqfDeLco0SRuIJmwSbFe0ocspsyywjzttDfKISum7YwLGdqnt/f8K9rj6A 43tQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=oSqDnSurul1SEUdPfy/k5oKwDRKz1lqnIF0nSiq8EfM=; b=J5yxf3QfY9LHb3uqnPrXiYYGyjbU8KNAZu/wCsN9M00x2hCFoc6RLUXk1R41nboNWT Ju3lO58yoH+q6ZoGPKGpn/pFi9EueCr7E2NCEheaaW6nWwo6ztJ53TwYvCVTY557gx2h QHtLvBf3vGdjk0iHXMO1ar/WxbaKKN5W0rAD9wm18cl9jJgE0j/8zjp6A3k0F2y6QkJQ y4jnAG9XSAcGqPmEArusK2wvMWnQtso/PHAbR1PKr57kXXaKDAPbBpyu26bqXSe82Djj HOuiEWDbBpop6A40rav6WqAfVl9OJrWAxJqt4//zU+L+i2uIZY89Uc+mOLFZtvGGbbPo z4YA== X-Gm-Message-State: AOAM530nOw7qxqqx2JT/lQNAyg+2nBLRpM4YXc+cmgcGs6LlDx3K7WAk XCPS7E/vzfj8+K8aXFn4whk= X-Google-Smtp-Source: ABdhPJwp5fFXpDXs+77u4RzzJOB/E/gElAzOw+O6qZWhP8oGIspsUZNfxr6ClFMkE+oplQc/U6Sj5w== X-Received: by 2002:aa7:9892:: with SMTP id r18mr8741441pfl.107.1599978056909; Sat, 12 Sep 2020 23:20:56 -0700 (PDT) Received: from [192.168.0.104] ([49.207.209.61]) by smtp.gmail.com with ESMTPSA id x9sm7031293pfj.96.2020.09.12.23.20.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 12 Sep 2020 23:20:56 -0700 (PDT) Subject: Re: [Linux-kernel-mentees] [PATCH] net: fix uninit value error in __sys_sendmmsg To: Greg KH Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jakub Kicinski , syzbot+09a5d591c1f98cf5efcb@syzkaller.appspotmail.com, "David S. Miller" , linux-kernel-mentees@lists.linuxfoundation.org References: <20200913055639.15639-1-anant.thazhemadam@gmail.com> <20200913061351.GA585618@kroah.com> From: Anant Thazhemadam Message-ID: <89526337-9657-8f4d-3022-9f2ad830fbe9@gmail.com> Date: Sun, 13 Sep 2020 11:50:52 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200913061351.GA585618@kroah.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 13/09/20 11:43 am, Greg KH wrote: > On Sun, Sep 13, 2020 at 11:26:39AM +0530, Anant Thazhemadam wrote: >> The crash report showed that there was a local variable; >> >> ----iovstack.i@__sys_sendmmsg created at: >> ___sys_sendmsg net/socket.c:2388 [inline] >> __sys_sendmmsg+0x6db/0xc90 net/socket.c:2480 >> >> that was left uninitialized. >> >> The contents of iovstack are of interest, since the respective pointer >> is passed down as an argument to sendmsg_copy_msghdr as well. >> Initializing this contents of this stack prevents this bug from happening. >> >> Since the memory that was initialized is freed at the end of the function >> call, memory leaks are not likely to be an issue. >> >> syzbot seems to have triggered this error by passing an array of 0's as >> a parameter while making the initial system call. >> >> Reported-by: syzbot+09a5d591c1f98cf5efcb@syzkaller.appspotmail.com >> Tested-by: syzbot+09a5d591c1f98cf5efcb@syzkaller.appspotmail.com >> Signed-off-by: Anant Thazhemadam >> --- >> net/socket.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/net/socket.c b/net/socket.c >> index 0c0144604f81..d74443dfd73b 100644 >> --- a/net/socket.c >> +++ b/net/socket.c >> @@ -2396,6 +2396,7 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg, >> { >> struct sockaddr_storage address; >> struct iovec iovstack[UIO_FASTIOV], *iov = iovstack; >> + memset(iov, 0, UIO_FASTIOV); >> ssize_t err; >> >> msg_sys->msg_name = &address; > I don't think you built this code change, otherwise you would have seen > that it adds a build warning to the system, right? > > :( My apologies. I think I ended up overlooking the build warning. Thank you for pointing that out. If everything else looks good, I'd be happy to send in a v2 that fixes this build warning. Thanks, Anant