From patchwork Tue Jul 14 01:27:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peilin Ye X-Patchwork-Id: 1328582 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=py84OM+5; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B5NGj2zhYz9sRR for ; Tue, 14 Jul 2020 11:29:33 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726619AbgGNB3b (ORCPT ); Mon, 13 Jul 2020 21:29:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726460AbgGNB3a (ORCPT ); Mon, 13 Jul 2020 21:29:30 -0400 Received: from mail-qk1-x742.google.com (mail-qk1-x742.google.com [IPv6:2607:f8b0:4864:20::742]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 936C7C061755; Mon, 13 Jul 2020 18:29:30 -0700 (PDT) Received: by mail-qk1-x742.google.com with SMTP id c30so14195428qka.10; Mon, 13 Jul 2020 18:29:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=R5IIzVMOgCGftVB47FAaShDA0o6roHJ+qQ1SXjjeBPw=; b=py84OM+5bG/8beCPdSOmQckjN7FoZchWH/ZlMsgqV0kEXJzeMI3pkaCzwYjHe8FN7q 7lkkAI/fQ4Bu8cS6E5f0PFiFL0D6+fhbm9SLHkASWNLELrUBTnIBwoEECSb+fHP52QMX svXQQgU+Sm9cq4s1ikEcdzccc5mS4h87wkIcsPIpApZRk5/yyyfSrZb67FBOxqWKVt95 lsAMYIkTgw/TZ+Hd4srf3NaLYg0Wp3lo2J2vWXGeKmhvr72JlJCzW1U9xftaXYJ06UCX 6e2yRiMobflrXWYyMLPittWrzTkFblzDCn/ay5piTeaLgkIxbVK3+xWqYGwammud6K4v D3Rg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=R5IIzVMOgCGftVB47FAaShDA0o6roHJ+qQ1SXjjeBPw=; b=CqerWyAImO6k7YCKx55S3ll4WqPw04l4qckjmxsNlvjCSE+xothRGg1qvhK7d1eOmi PK96srrEdms33KPVzmmNXQ6bgWpANUDehyCkNFgrJpE4iiOBR6wgCgNyXd18V+bBER5W U6/WBeAs9dWMRfH16h3RXHlBn6A2BhvfjvFRT70cGO8Npu2FDcM3f3VIkrXK49HljdkL 7dP02AAtO66bVvNeENLRSt6ThwHFMCtltEhC+l1KvlLiMB1M4BY2udxVY+aGpwX+gBhR hP7JQ0fvYmQXNYAauDVZBa4Phq6vkRkl3MiwHcRaHY1kNFkKFOoG4KpzlYPKXtZGZDOi rwSQ== X-Gm-Message-State: AOAM532htHZ9YM7uywImzTmx/tIRuA4zpXsjcKU8z5m80A0jQxsZdhSJ QnvCQorKbr+g8VSvoia11A== X-Google-Smtp-Source: ABdhPJwiHJEuFip+53k+1C0OC/E9TC3f8o1MxGFmfFAYhf0A8tB6Hb8t/KlSZbhCmgIH8HWpRiLTYw== X-Received: by 2002:ae9:ea13:: with SMTP id f19mr2317534qkg.331.1594690169776; Mon, 13 Jul 2020 18:29:29 -0700 (PDT) Received: from localhost.localdomain ([209.94.141.207]) by smtp.gmail.com with ESMTPSA id w28sm19125827qkw.92.2020.07.13.18.29.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jul 2020 18:29:29 -0700 (PDT) From: Peilin Ye To: Andrii Nakryiko Cc: Peilin Ye , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Greg Kroah-Hartman , netdev@vger.kernel.org, bpf@vger.kernel.org, syzkaller-bugs@googlegroups.com, linux-kernel-mentees@lists.linuxfoundation.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [Linux-kernel-mentees] [PATCH v2] bpf: Fix NULL pointer dereference in __btf_resolve_helper_id() Date: Mon, 13 Jul 2020 21:27:32 -0400 Message-Id: <20200714012732.195466-1-yepeilin.cs@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org 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 Acked-by: Andrii Nakryiko --- Thank you for reviewing my patch! I am new to Linux kernel development; would the log message and errno be appropriate for this case? Change in v2: - Split NULL and IS_ERR cases. kernel/bpf/btf.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 30721f2c2d10..092116a311f4 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4088,6 +4088,11 @@ static int __btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn, const char *tname, *sym; u32 btf_id, i; + if (!btf_vmlinux) { + bpf_log(log, "btf_vmlinux doesn't exist\n"); + return -EINVAL; + } + if (IS_ERR(btf_vmlinux)) { bpf_log(log, "btf_vmlinux is malformed\n"); return -EINVAL;