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 686C7ECAAD5 for ; Fri, 26 Aug 2022 23:16:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345456AbiHZXQR convert rfc822-to-8bit (ORCPT ); Fri, 26 Aug 2022 19:16:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345227AbiHZXQQ (ORCPT ); Fri, 26 Aug 2022 19:16:16 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7113FDFB7B for ; Fri, 26 Aug 2022 16:16:15 -0700 (PDT) Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 27QIP8Cu017925 for ; Fri, 26 Aug 2022 16:16:14 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3j6g8e09q7-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 26 Aug 2022 16:16:14 -0700 Received: from snc-exhub201.TheFacebook.com (2620:10d:c085:21d::7) by snc-exhub202.TheFacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 26 Aug 2022 16:16:11 -0700 Received: from twshared16308.14.prn3.facebook.com (2620:10d:c085:208::f) 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, 26 Aug 2022 16:15:43 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 24FF61E283E4C; Fri, 26 Aug 2022 16:15:38 -0700 (PDT) From: Andrii Nakryiko To: , , CC: , Subject: [PATCH bpf-next 2/3] libbpf: fix crash if SEC("freplace") programs don't have attach_prog_fd set Date: Fri, 26 Aug 2022 16:15:30 -0700 Message-ID: <20220826231531.1031943-3-andrii@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220826231531.1031943-1-andrii@kernel.org> References: <20220826231531.1031943-1-andrii@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: g5ryVDM8IWduYrneS4SZPiaam29MRXiO X-Proofpoint-ORIG-GUID: g5ryVDM8IWduYrneS4SZPiaam29MRXiO X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-26_12,2022-08-25_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