From patchwork Wed Apr 22 09:58:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 227231 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 CA9E4C55189 for ; Wed, 22 Apr 2020 10:28:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6FE92071E for ; Wed, 22 Apr 2020 10:28:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587551291; bh=aLEexzmvFjZs+xrFTUh+Epi0eEaW4BXGZTMzypmLQtI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=u6/BrCtpViWMRG9ce5psdchi25+WrQvNofSqOC5alkrDqU+HcWogkhzz0+vekeroD hUlvORKo0LmH8oNTmdHpiVRossDN5mCrDvjEbosP+9LR6pubMB3FrOCi/gQ6whqa2d rRFqN9GR/AQHQ3/5w1r7uKBVwDWEvlyPgn2quBhE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730973AbgDVK2A (ORCPT ); Wed, 22 Apr 2020 06:28:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:37248 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730418AbgDVK17 (ORCPT ); Wed, 22 Apr 2020 06:27:59 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 52F8B2098B; Wed, 22 Apr 2020 10:27:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587551278; bh=aLEexzmvFjZs+xrFTUh+Epi0eEaW4BXGZTMzypmLQtI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VHORauBwY+mujz8ddtLXagAuv0A2wo3ugRAGcf4l9gyDW0LXj/tT1zVJ+nWv3cn3+ dAU+pZCUw/pHBVIbb8XfsqiilZphMXxCXm3lQ/IpQs1o2vggyEni3RK8YeXY2p6F/7 ZrTqCSmbvCgGoBDgj5z2p+Nl88je9wm8t8pxdhZs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , John Fastabend Subject: [PATCH 5.6 166/166] bpf, test_verifier: switch bpf_get_stacks 0 s> r8 test Date: Wed, 22 Apr 2020 11:58:13 +0200 Message-Id: <20200422095106.153738046@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095047.669225321@linuxfoundation.org> References: <20200422095047.669225321@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Daniel Borkmann [ no upstream commit ] Switch the comparison, so that is_branch_taken() will recognize that below branch is never taken: [...] 17: [...] R1_w=inv0 [...] R8_w=inv(id=0,smin_value=-2147483648,smax_value=-1,umin_value=18446744071562067968,var_off=(0xffffffff80000000; 0x7fffffff)) [...] 17: (67) r8 <<= 32 18: [...] R8_w=inv(id=0,smax_value=-4294967296,umin_value=9223372036854775808,umax_value=18446744069414584320,var_off=(0x8000000000000000; 0x7fffffff00000000)) [...] 18: (c7) r8 s>>= 32 19: [...] R8_w=inv(id=0,smin_value=-2147483648,smax_value=-1,umin_value=18446744071562067968,var_off=(0xffffffff80000000; 0x7fffffff)) [...] 19: (6d) if r1 s> r8 goto pc+16 [...] R1_w=inv0 [...] R8_w=inv(id=0,smin_value=-2147483648,smax_value=-1,umin_value=18446744071562067968,var_off=(0xffffffff80000000; 0x7fffffff)) [...] [...] Currently we check for is_branch_taken() only if either K is source, or source is a scalar value that is const. For upstream it would be good to extend this properly to check whether dst is const and src not. For the sake of the test_verifier, it is probably not needed here: # ./test_verifier 101 #101/p bpf_get_stack return R0 within range OK Summary: 1 PASSED, 0 SKIPPED, 0 FAILED I haven't seen this issue in test_progs* though, they are passing fine: # ./test_progs-no_alu32 -t get_stack Switching to flavor 'no_alu32' subdirectory... #20 get_stack_raw_tp:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED # ./test_progs -t get_stack #20 get_stack_raw_tp:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Acked-by: John Fastabend Signed-off-by: Greg Kroah-Hartman --- tools/testing/selftests/bpf/verifier/bpf_get_stack.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/tools/testing/selftests/bpf/verifier/bpf_get_stack.c +++ b/tools/testing/selftests/bpf/verifier/bpf_get_stack.c @@ -19,7 +19,7 @@ BPF_MOV64_REG(BPF_REG_8, BPF_REG_0), BPF_ALU64_IMM(BPF_LSH, BPF_REG_8, 32), BPF_ALU64_IMM(BPF_ARSH, BPF_REG_8, 32), - BPF_JMP_REG(BPF_JSGT, BPF_REG_1, BPF_REG_8, 16), + BPF_JMP_REG(BPF_JSLT, BPF_REG_8, BPF_REG_1, 16), BPF_ALU64_REG(BPF_SUB, BPF_REG_9, BPF_REG_8), BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_8),