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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 61961C433F5 for ; Mon, 4 Oct 2021 13:38:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43728611C0 for ; Mon, 4 Oct 2021 13:38:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238128AbhJDNjy (ORCPT ); Mon, 4 Oct 2021 09:39:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:51966 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238153AbhJDNhI (ORCPT ); Mon, 4 Oct 2021 09:37:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1D3CB6124B; Mon, 4 Oct 2021 13:16:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1633353405; bh=KMlCW3ihomlYIXeJo//98hTRu56y/+zQROHmuNdSJxs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tGao5fDQOLiNRM2qS1FbavaTBSS4P6myoWir72up5/k4Qcwsjb4Ftf7iDC9iNbFcn 2MqOvfFIZsNLTzaUeqaYHh2YpMt3gaHI5I2gwnHUCGqMGEcQJKRU85x3ifqnwMDgeK v4luCo4+8OGFd2acvymW5gqiX5C+s9JQgl8eA2ag= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kumar Kartikeya Dwivedi , Andrii Nakryiko , Daniel Borkmann , Sasha Levin Subject: [PATCH 5.14 115/172] libbpf: Fix segfault in static linker for objects without BTF Date: Mon, 4 Oct 2021 14:52:45 +0200 Message-Id: <20211004125048.693992509@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211004125044.945314266@linuxfoundation.org> References: <20211004125044.945314266@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kumar Kartikeya Dwivedi [ Upstream commit bcfd367c2839f2126c048fe59700ec1b538e2b06 ] When a BPF object is compiled without BTF info (without -g), trying to link such objects using bpftool causes a SIGSEGV due to btf__get_nr_types accessing obj->btf which is NULL. Fix this by checking for the NULL pointer, and return error. Reproducer: $ cat a.bpf.c extern int foo(void); int bar(void) { return foo(); } $ cat b.bpf.c int foo(void) { return 0; } $ clang -O2 -target bpf -c a.bpf.c $ clang -O2 -target bpf -c b.bpf.c $ bpftool gen obj out a.bpf.o b.bpf.o Segmentation fault (core dumped) After fix: $ bpftool gen obj out a.bpf.o b.bpf.o libbpf: failed to find BTF info for object 'a.bpf.o' Error: failed to link 'a.bpf.o': Unknown error -22 (-22) Fixes: a46349227cd8 (libbpf: Add linker extern resolution support for functions and global variables) Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210924023725.70228-1-memxor@gmail.com Signed-off-by: Sasha Levin --- tools/lib/bpf/linker.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c index 10911a8cad0f..2df880cefdae 100644 --- a/tools/lib/bpf/linker.c +++ b/tools/lib/bpf/linker.c @@ -1649,11 +1649,17 @@ static bool btf_is_non_static(const struct btf_type *t) static int find_glob_sym_btf(struct src_obj *obj, Elf64_Sym *sym, const char *sym_name, int *out_btf_sec_id, int *out_btf_id) { - int i, j, n = btf__get_nr_types(obj->btf), m, btf_id = 0; + int i, j, n, m, btf_id = 0; const struct btf_type *t; const struct btf_var_secinfo *vi; const char *name; + if (!obj->btf) { + pr_warn("failed to find BTF info for object '%s'\n", obj->filename); + return -EINVAL; + } + + n = btf__get_nr_types(obj->btf); for (i = 1; i <= n; i++) { t = btf__type_by_id(obj->btf, i); -- 2.33.0