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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6499C6FA89 for ; Fri, 9 Sep 2022 19:31:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229544AbiIITbU convert rfc822-to-8bit (ORCPT ); Fri, 9 Sep 2022 15:31:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229563AbiIITbS (ORCPT ); Fri, 9 Sep 2022 15:31:18 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A2B4D99F4 for ; Fri, 9 Sep 2022 12:31:16 -0700 (PDT) Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 289Er5kA026411 for ; Fri, 9 Sep 2022 12:31:15 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3jfqedf3xk-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 09 Sep 2022 12:31:15 -0700 Received: from snc-exhub201.TheFacebook.com (2620:10d:c085:21d::7) by snc-exhub102.TheFacebook.com (2620:10d:c085:11d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 9 Sep 2022 12:31:13 -0700 Received: from twshared6447.05.prn5.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:21d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 9 Sep 2022 12:31:13 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 318D71EB4F6F6; Fri, 9 Sep 2022 12:30:59 -0700 (PDT) From: Andrii Nakryiko To: , , CC: , Subject: [PATCH v2 bpf-next 2/3] libbpf: fix crash if SEC("freplace") programs don't have attach_prog_fd set Date: Fri, 9 Sep 2022 12:30:52 -0700 Message-ID: <20220909193053.577111-3-andrii@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220909193053.577111-1-andrii@kernel.org> References: <20220909193053.577111-1-andrii@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: WHzCJ1LF5NgQHCC5X7TfGjpzMPqxquCD X-Proofpoint-ORIG-GUID: WHzCJ1LF5NgQHCC5X7TfGjpzMPqxquCD X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-09_10,2022-09-09_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Fix SIGSEGV caused by libbpf trying to find attach type in vmlinux BTF for freplace programs. It's wrong to search in vmlinux BTF and libbpf doesn't even mark vmlinux BTF as required for freplace programs. So trying to search anything in obj->vmlinux_btf might cause NULL dereference if nothing else in BPF object requires vmlinux BTF. Instead, error out if freplace (EXT) program doesn't specify attach_prog_fd during at the load time. Fixes: 91abb4a6d79d ("libbpf: Support attachment of BPF tracing programs to kernel modules") Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 3ad139285fad..2ca30ccc774c 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -9084,11 +9084,15 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attac int err = 0; /* BPF program's BTF ID */ - if (attach_prog_fd) { + if (prog->type == BPF_PROG_TYPE_EXT || attach_prog_fd) { + if (!attach_prog_fd) { + pr_warn("prog '%s': attach program FD is not set\n", prog->name); + return -EINVAL; + } err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd); if (err < 0) { - pr_warn("failed to find BPF program (FD %d) BTF ID for '%s': %d\n", - attach_prog_fd, attach_name, err); + pr_warn("prog '%s': failed to find BPF program (FD %d) BTF ID for '%s': %d\n", + prog->name, attach_prog_fd, attach_name, err); return err; } *btf_obj_fd = 0; @@ -9105,7 +9109,8 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attac err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id); } if (err) { - pr_warn("failed to find kernel BTF type ID of '%s': %d\n", attach_name, err); + pr_warn("prog '%s': failed to find kernel BTF type ID of '%s': %d\n", + prog->name, attach_name, err); return err; } return 0; -- 2.30.2