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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5F81C47097 for ; Thu, 3 Jun 2021 17:07:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D306C6140A for ; Thu, 3 Jun 2021 17:07:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230339AbhFCRJ0 (ORCPT ); Thu, 3 Jun 2021 13:09:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:40338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230333AbhFCRJ0 (ORCPT ); Thu, 3 Jun 2021 13:09:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 809F2613DE; Thu, 3 Jun 2021 17:07:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622740061; bh=27kYeqCQHC+7oB//+3h8Rl8uVvRD+9U76fLMbkQRlsM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CqTVKze93Vgeq3OA+NL8bli3d2jPLOMNlfv2VC33pBPKxt/QzFdMElrrnPsfZfLtV pLbMCmaruE3lYL8skMAgNlwQDfYwOo4bwf4dCILIJ6RcY7RggrFfByp2FJnRzyc7fU a9wlCD1KGEwN6/GQVNkjIWuYuvXNE9cDjZQIupnpFMEqPQnyYYM8zSz/8DphLm5lWP V7fX31HJDsPA+pSPDUboGHPk+LU9Xn68dYc+bUZG7FogIIjt5fDT6zNp5IJbiuxE2C 3Z4MIfIOc/dhuLfmIIR5NARxV7QP816+ahECz+EmhEZO2kgCZnQbJKKdO1+mvm6vff VUuSeXzmfi/fw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jiri Olsa , Daniel Borkmann , Andrii Nakryiko , Sasha Levin , netdev@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH AUTOSEL 5.12 05/43] bpf: Forbid trampoline attach for functions with variable arguments Date: Thu, 3 Jun 2021 13:06:55 -0400 Message-Id: <20210603170734.3168284-5-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210603170734.3168284-1-sashal@kernel.org> References: <20210603170734.3168284-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: Jiri Olsa [ Upstream commit 31379397dcc364a59ce764fabb131b645c43e340 ] We can't currently allow to attach functions with variable arguments. The problem is that we should save all the registers for arguments, which is probably doable, but if caller uses more than 6 arguments, we need stack data, which will be wrong, because of the extra stack frame we do in bpf trampoline, so we could crash. Also currently there's malformed trampoline code generated for such functions at the moment as described in: https://lore.kernel.org/bpf/20210429212834.82621-1-jolsa@kernel.org/ Signed-off-by: Jiri Olsa Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210505132529.401047-1-jolsa@kernel.org Signed-off-by: Sasha Levin --- kernel/bpf/btf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index b1a76fe046cb..6bd003568fa5 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5126,6 +5126,12 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, m->ret_size = ret; for (i = 0; i < nargs; i++) { + if (i == nargs - 1 && args[i].type == 0) { + bpf_log(log, + "The function %s with variable args is unsupported.\n", + tname); + return -EINVAL; + } ret = __get_type_size(btf, args[i].type, &t); if (ret < 0) { bpf_log(log, @@ -5133,6 +5139,12 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, tname, i, btf_kind_str[BTF_INFO_KIND(t->info)]); return -EINVAL; } + if (ret == 0) { + bpf_log(log, + "The function %s has malformed void argument.\n", + tname); + return -EINVAL; + } m->arg_size[i] = ret; } m->nr_args = nargs; -- 2.30.2