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 7E67FC678D4 for ; Tue, 7 Mar 2023 17:21:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230411AbjCGRVI (ORCPT ); Tue, 7 Mar 2023 12:21:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230373AbjCGRUo (ORCPT ); Tue, 7 Mar 2023 12:20:44 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAE929FBE5 for ; Tue, 7 Mar 2023 09:16:01 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 53AFEB819A9 for ; Tue, 7 Mar 2023 17:16:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA9DDC433EF; Tue, 7 Mar 2023 17:15:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678209359; bh=7N6oifyHFC1nqqyYt3My57NdM3Hfok8rcw3GmbacoI4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XhnBhS1ccjgh4DVXu117S0ymjAnla1YuKDMQaipM8DmCoqCiQhEL2YCTqH/aZTjbo JWZBD0igRXiy3zcmwrW+A70Gj1/w1bxXd4ZPyfoV3BNapSspDGcNrxU/uVFbVcCjt3 AoBxr/9HfNpdGvgRGm3SRBvKbMCkajdrtKonhgE4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrii Nakryiko , Daniel Borkmann , Sasha Levin Subject: [PATCH 6.2 0161/1001] libbpf: Fix btf__align_of() by taking into account field offsets Date: Tue, 7 Mar 2023 17:48:53 +0100 Message-Id: <20230307170029.008701547@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170022.094103862@linuxfoundation.org> References: <20230307170022.094103862@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Andrii Nakryiko [ Upstream commit 25a4481b4136af7794e1df2d6c90ed2f354d60ce ] btf__align_of() is supposed to be return alignment requirement of a requested BTF type. For STRUCT/UNION it doesn't always return correct value, because it calculates alignment only based on field types. But for packed structs this is not enough, we need to also check field offsets and struct size. If field offset isn't aligned according to field type's natural alignment, then struct must be packed. Similarly, if struct size is not a multiple of struct's natural alignment, then struct must be packed as well. This patch fixes this issue precisely by additionally checking these conditions. Fixes: 3d208f4ca111 ("libbpf: Expose btf__align_of() API") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20221212211505.558851-5-andrii@kernel.org Signed-off-by: Sasha Levin --- tools/lib/bpf/btf.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 71e165b09ed59..8cbcef959456d 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -688,8 +688,21 @@ int btf__align_of(const struct btf *btf, __u32 id) if (align <= 0) return libbpf_err(align); max_align = max(max_align, align); + + /* if field offset isn't aligned according to field + * type's alignment, then struct must be packed + */ + if (btf_member_bitfield_size(t, i) == 0 && + (m->offset % (8 * align)) != 0) + return 1; } + /* if struct/union size isn't a multiple of its alignment, + * then struct must be packed + */ + if ((t->size % max_align) != 0) + return 1; + return max_align; } default: -- 2.39.2