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 DD385C433F5 for ; Thu, 30 Sep 2021 06:16:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE39661527 for ; Thu, 30 Sep 2021 06:16:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348255AbhI3GSU (ORCPT ); Thu, 30 Sep 2021 02:18:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348254AbhI3GST (ORCPT ); Thu, 30 Sep 2021 02:18:19 -0400 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8704BC06161C for ; Wed, 29 Sep 2021 23:16:37 -0700 (PDT) Received: by mail-pg1-x542.google.com with SMTP id e7so5192625pgk.2 for ; Wed, 29 Sep 2021 23:16:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=Pb2OlO3FWknzLv3NgAHRQB3w1rBIwUIdDtYVy8/uF8g=; b=jeKOknwf5pYwqmgYuM7Q9ZgP8N1//E1CutSqisSu+14FE6kQHHdED/wFY/0WEp5/tl NR0Rc5wkiugmwbyGOPY0rfsfOq4MhhbgGqBNMsNKWp9B4BaqlfCXu90cJbZZUW/O6YSA kdXlr0avqxCFtPK5m7DOptw9kG5g0Spu0z3N/ulh+Ypw5SMo3jh4GRtY6AhPJRfRTyKy mdPfZ0A3VF+dSWKUPFfTYzTP91ABcc6mIfVE2buH8DK8fqVidugm7F/+lLz7vMdc09Gi 4oeAEaWcdilHSBrbMqcF/wRK3qcHPuLYSmhqufc9vEfZNz/GXC6O4HDU/oAkJyrjVT7p FjLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=Pb2OlO3FWknzLv3NgAHRQB3w1rBIwUIdDtYVy8/uF8g=; b=OplyYxFOcJez3bJGJmHXFF383QQn7fA6ynJVB0c3bE5Mtfdk7XatVk8yNVdxIMYmoC pL7AtUFco6mJfCxxBIiylN47HSXo8/FDPPv79QqFCGUwIL+9UWicWUHnSnS3BBLuyudx YtbmGIDfzJfZkY4jaccYQ4LvdVa7Zdvo1xCFFobrZCst5kvzql97RsLdwssP9ajJsg85 Pm2bmlj0Af9NXoU2kFD4meHhRPdWz4FYBNqUcuW1t4maizTTgDbYS68FonL2BLGUh2KB pWZdx78hUxebyV8qVoUpAepOAXGDuZHf1cPlA4rCj03Pq9SVHm5MaaUxpNKpTYXCzW89 mlpg== X-Gm-Message-State: AOAM530V0i8OAbdaiixbqNVdx3eYYvDJ6AIzevlpEnA+iiZdTXBfx8ZV DQ6n+FotAWWzbjEhT16PdY6XbHjIk+M= X-Google-Smtp-Source: ABdhPJwdjUeBK0kfa38CYBqkgVrDB/t2XDsPYLdVtVdvOIXHSTLL/bbd4QkFiiCd3AQYOYkT+/Ocqg== X-Received: by 2002:a63:d351:: with SMTP id u17mr3457618pgi.174.1632982596808; Wed, 29 Sep 2021 23:16:36 -0700 (PDT) Received: from localhost ([2405:201:6014:d058:a28d:3909:6ed5:29e7]) by smtp.gmail.com with ESMTPSA id 23sm1777141pfw.97.2021.09.29.23.16.36 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Sep 2021 23:16:36 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Subject: [PATCH bpf] libbpf: Fix segfault in light skeleton for objects without BTF Date: Thu, 30 Sep 2021 11:46:34 +0530 Message-Id: <20210930061634.1840768-1-memxor@gmail.com> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org When fed an empty BPF object, bpftool gen skeleton -L crashes at btf__set_fd since it assumes presence of obj->btf, however for the sequence below clang adds no .BTF section (hence no BTF). Reproducer: $ touch a.bpf.c $ clang -O2 -g -target bpf -c a.bpf.c $ bpftool gen skeleton -L a.bpf.o /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ /* THIS FILE IS AUTOGENERATED! */ struct a_bpf { struct bpf_loader_ctx ctx; Segmentation fault (core dumped) The same occurs for files compiled without BTF info, i.e. without clang's -g flag. Fixes: 67234743736a (libbpf: Generate loader program out of BPF ELF file.) Signed-off-by: Kumar Kartikeya Dwivedi --- tools/lib/bpf/libbpf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0f85d441fca3..b6b130171b86 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -7031,7 +7031,8 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr) if (obj->gen_loader) { /* reset FDs */ - btf__set_fd(obj->btf, -1); + if (obj->btf) + btf__set_fd(obj->btf, -1); for (i = 0; i < obj->nr_maps; i++) obj->maps[i].fd = -1; if (!err) -- 2.33.0