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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 64A4EC35257 for ; Wed, 16 Sep 2020 18:56:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D3CC20809 for ; Wed, 16 Sep 2020 18:56:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="gcsXLtK2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727657AbgIPS4d (ORCPT ); Wed, 16 Sep 2020 14:56:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727662AbgIPRyS (ORCPT ); Wed, 16 Sep 2020 13:54:18 -0400 Received: from mail-wm1-x344.google.com (mail-wm1-x344.google.com [IPv6:2a00:1450:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADACAC061788 for ; Wed, 16 Sep 2020 10:53:34 -0700 (PDT) Received: by mail-wm1-x344.google.com with SMTP id z9so3953011wmk.1 for ; Wed, 16 Sep 2020 10:53:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=+Qf5LrUrrFDb7ZG/DC+Ibysm2jzcOs3sVRYjuHbV+04=; b=gcsXLtK2CLLricYdGQQrTG2/QyorwaXXvCFHPWJwmsmpqNRdexAc9QcrbMt9z0Qra/ Ym4j5LDElNP+RkwCF5CRfkEJwbAFFvEKjyHl75IFC0Vb/lP/L11yioBY/qJ0XUYp+ote T7rj52Kx4BVTgr9HOJYJzB/C4dUEvWQFKlo8U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=+Qf5LrUrrFDb7ZG/DC+Ibysm2jzcOs3sVRYjuHbV+04=; b=TxmcO4y/mIfePVM7Ax44BDdR3axwcINJthwt1TawZ5nTWaS4XLgk4MP3OmPuh7noQ5 OhKSBXntIxcRgwnffZR5Fa0Gbr0fO0qARC1OB6HWipfLJmA8cCSd6Tx2335YCto92PlH lggUgTia6rXsLRgAlbKYFhZvGCWRScYZpTYcNwAMzciRziWLJbeaEqfprSYxMhcamYEf vLarsl7B8Fkr0GcHAO6GVkL+K6lN0LhgBjz2/zVdLkofCTOwIcM1Q2I0H+m/c9vli9Cx OR9weRQmrxK6eDwp9JafT40o7nPT1YUWSxE0ckrtqZo+oEMqkvDmAnqztpbJepj4wCVC P1Fw== X-Gm-Message-State: AOAM532Hbsml0IieKkRvX6zzyPEjyF0dZi5yOT8wjwiz8UbBXIgab4y6 dF5jZZgehRgaE00dsRqK3fdzd1O6Rb0X3g== X-Google-Smtp-Source: ABdhPJyr+UlGu5TjPG/Eez8but8mH08awWsPpjzQx9tNb1AiE+oIGrmeO0mLO2WD68MoWVwzjFM1tw== X-Received: by 2002:a1c:96:: with SMTP id 144mr6003155wma.84.1600278813380; Wed, 16 Sep 2020 10:53:33 -0700 (PDT) Received: from antares.lan (5.c.5.5.a.2.f.6.a.a.d.6.3.1.9.1.f.f.6.2.a.5.a.7.0.b.8.0.1.0.0.2.ip6.arpa. [2001:8b0:7a5a:26ff:1913:6daa:6f2a:55c5]) by smtp.gmail.com with ESMTPSA id v17sm34177508wrr.60.2020.09.16.10.53.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Sep 2020 10:53:32 -0700 (PDT) From: Lorenz Bauer To: ast@kernel.org, yhs@fb.com, daniel@iogearbox.net, kafai@fb.com, andriin@fb.com Cc: bpf@vger.kernel.org, kernel-team@cloudflare.com, Lorenz Bauer Subject: [PATCH bpf-next v4 02/11] bpf: check scalar or invalid register in check_helper_mem_access Date: Wed, 16 Sep 2020 18:52:46 +0100 Message-Id: <20200916175255.192040-3-lmb@cloudflare.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200916175255.192040-1-lmb@cloudflare.com> References: <20200916175255.192040-1-lmb@cloudflare.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Move the check for a NULL or zero register to check_helper_mem_access. This makes check_stack_boundary easier to understand. Signed-off-by: Lorenz Bauer Acked-by: Andrii Nakryiko --- kernel/bpf/verifier.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 814bc6c1ad16..c997f81c500b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3594,18 +3594,6 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno, struct bpf_func_state *state = func(env, reg); int err, min_off, max_off, i, j, slot, spi; - if (reg->type != PTR_TO_STACK) { - /* Allow zero-byte read from NULL, regardless of pointer type */ - if (zero_size_allowed && access_size == 0 && - register_is_null(reg)) - return 0; - - verbose(env, "R%d type=%s expected=%s\n", regno, - reg_type_str[reg->type], - reg_type_str[PTR_TO_STACK]); - return -EACCES; - } - if (tnum_is_const(reg->var_off)) { min_off = max_off = reg->var_off.value + reg->off; err = __check_stack_boundary(env, regno, min_off, access_size, @@ -3750,9 +3738,19 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, access_size, zero_size_allowed, "rdwr", &env->prog->aux->max_rdwr_access); - default: /* scalar_value|ptr_to_stack or invalid ptr */ + case PTR_TO_STACK: return check_stack_boundary(env, regno, access_size, zero_size_allowed, meta); + default: /* scalar_value or invalid ptr */ + /* Allow zero-byte read from NULL, regardless of pointer type */ + if (zero_size_allowed && access_size == 0 && + register_is_null(reg)) + return 0; + + verbose(env, "R%d type=%s expected=%s\n", regno, + reg_type_str[reg->type], + reg_type_str[PTR_TO_STACK]); + return -EACCES; } } -- 2.25.1