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=-10.1 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,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B0372C433E8 for ; Tue, 14 Jul 2020 00:53:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E76F217BA for ; Tue, 14 Jul 2020 00:53:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rMiR71v/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727044AbgGNAxn (ORCPT ); Mon, 13 Jul 2020 20:53:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726918AbgGNAxl (ORCPT ); Mon, 13 Jul 2020 20:53:41 -0400 Received: from mail-qk1-x743.google.com (mail-qk1-x743.google.com [IPv6:2607:f8b0:4864:20::743]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C2E4C061755; Mon, 13 Jul 2020 17:53:41 -0700 (PDT) Received: by mail-qk1-x743.google.com with SMTP id l6so14146817qkc.6; Mon, 13 Jul 2020 17:53:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=bpaDsBvlz9opHaHnQGrx2N2C4SwE84lnQr92+oDq3LY=; b=rMiR71v/yR8fu0eB1iPdEzuhUbc3Mny0j9rhKZSyWfs+1MHiJRYvhF82OKFiwcI3X9 XeiFgk1K/dR0TL1vVCF/lQSSqa/gD4mrnxOYM7tt+DvJ2oPoGd95uW8w15LKE8GzZOTn uJnZET35qb/G0NspQbaiwdvxGR7/QENEyDYKFWc5nkbymOswflogUc1UIV7n0pZFuspi A5ouCCNm08KU7a96OiZ/WsFZN9Szb1Teoup51io8Dt4X1WWmakOZN4IA2+3gFZ32JTVN /35A7tqKPg6tE0rU+Q8HBN4pXEmq040XQusOlSB/q1e9mKPGYVxJBMQwlkjhSrz+QdxU NvUg== 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=bpaDsBvlz9opHaHnQGrx2N2C4SwE84lnQr92+oDq3LY=; b=HOA2O+D8Uwl7X1bZaUOdlNFJVx6yGypyejlT4YX7JZJqCoppK3iZ8AjXxikmZzy5fN 8kH+KPwibIQoXBB47C4pHS4M+FoXKAPj7ZUQijhgoe/VW2F+9pEIs1bffAbzYwpNqWSc PWgtJ/6ihTsrM5eYDQUlRDdlfbwXE96HUNm1Vp2+oNfLxAhb7XZhCh2+hnrI4RFSUc28 gT6knMpNy0d/m4yg/nIOvvIJ/DL8fhoiL3KDyDOHsdoetNAd30oGm/9f5fun4KG59ett zBzLswDESEXl1+Jl6eZkLgNoyLXkpobtvVoYvni4JfE5dqLXyyqkegsGvIhKk5VEVXhA fLGw== X-Gm-Message-State: AOAM530qsF1RfiZ9e+WjhoIgbSW+vv1JcQEhwYjBbzbcJKE7Q7jfg1UX yB3f890bY3YYO6oBsVXkRG1XSC4fEnXSJxc2Nwo= X-Google-Smtp-Source: ABdhPJznFhGSinelKiS7+HI+X4/sqgLA5sTa9+gPEz/8nzGxBgAA+YLhuelXQUf40NcKOvz88GZRILG2qCFPv1ILg6w= X-Received: by 2002:a37:7683:: with SMTP id r125mr2256135qkc.39.1594688020649; Mon, 13 Jul 2020 17:53:40 -0700 (PDT) MIME-Version: 1.0 References: <20200714003856.194768-1-yepeilin.cs@gmail.com> In-Reply-To: <20200714003856.194768-1-yepeilin.cs@gmail.com> From: Andrii Nakryiko Date: Mon, 13 Jul 2020 17:53:28 -0700 Message-ID: Subject: Re: [Linux-kernel-mentees] [PATCH] bpf: Fix NULL pointer dereference in __btf_resolve_helper_id() To: Peilin Ye Cc: Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , Greg Kroah-Hartman , Networking , bpf , syzkaller-bugs@googlegroups.com, linux-kernel-mentees@lists.linuxfoundation.org, open list , clang-built-linux Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jul 13, 2020 at 5:43 PM Peilin Ye wrote: > > Prevent __btf_resolve_helper_id() from dereferencing `btf_vmlinux` > as NULL. This patch fixes the following syzbot bug: > > https://syzkaller.appspot.com/bug?id=5edd146856fd513747c1992442732e5a0e9ba355 > > Reported-by: syzbot+ee09bda7017345f1fbe6@syzkaller.appspotmail.com > Signed-off-by: Peilin Ye > --- > kernel/bpf/btf.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 30721f2c2d10..3e981b183fa4 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -4088,7 +4088,7 @@ static int __btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn, > const char *tname, *sym; > u32 btf_id, i; > > - if (IS_ERR(btf_vmlinux)) { > + if (IS_ERR_OR_NULL(btf_vmlinux)) { > bpf_log(log, "btf_vmlinux is malformed\n"); Can you please split IS_ERR and NULL cases and emit different messages to log? If the kernel is not built with btf_vmlinux, saying that it's "malformed" will confuse people. Thanks. > return -EINVAL; > } > -- > 2.25.1 >