From patchwork Fri Jun 3 01:59:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 12868435 X-Patchwork-Delegate: bpf@iogearbox.net 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 075BDC43334 for ; Fri, 3 Jun 2022 01:59:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236098AbiFCB7W (ORCPT ); Thu, 2 Jun 2022 21:59:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47486 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230167AbiFCB7V (ORCPT ); Thu, 2 Jun 2022 21:59:21 -0400 Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC6BC39696 for ; Thu, 2 Jun 2022 18:59:20 -0700 (PDT) Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.17.1.5/8.17.1.5) with ESMTP id 2530qiLe016101 for ; Thu, 2 Jun 2022 18:59:20 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=dtUFLurAVpC2sjwYufq4sMNqVj3+whNProPCHEfGRkw=; b=kSOxSqBw8XnzZxk4BEHHwfcfsaba2rPoZYuAHVH0Ql9YJn7hr+h1iSAq/MLOT5JJAIH2 jWhU5YQl+8uRH22NQMR4+yg6YijzbGmpJWiPaF7v9eiYpkfgbN2ApxcNTKXgSeNcCYHT 7Zv0dc98DyzBiuE783lPRlqC0jvQ7gC2ZU0= Received: from maileast.thefacebook.com ([163.114.130.16]) by m0089730.ppops.net (PPS) with ESMTPS id 3gf4yy97p8-19 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 02 Jun 2022 18:59:20 -0700 Received: from twshared24024.25.frc3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Thu, 2 Jun 2022 18:59:18 -0700 Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id 00D8DB299F4A; Thu, 2 Jun 2022 18:59:10 -0700 (PDT) From: Yonghong Song To: CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , , Dave Marchevsky Subject: [PATCH bpf-next v4 03/18] libbpf: Fix an error in 64bit relocation value computation Date: Thu, 2 Jun 2022 18:59:10 -0700 Message-ID: <20220603015910.1188721-1-yhs@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220603015855.1187538-1-yhs@fb.com> References: <20220603015855.1187538-1-yhs@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: fs-IEXl5v_1-VaVglA99KZPyRVHH2Y2S X-Proofpoint-ORIG-GUID: fs-IEXl5v_1-VaVglA99KZPyRVHH2Y2S X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-03_01,2022-06-02_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Currently, the 64bit relocation value in the instruction is computed as follows: __u64 imm = insn[0].imm + ((__u64)insn[1].imm << 32) Suppose insn[0].imm = -1 (0xffffffff) and insn[1].imm = 1. With the above computation, insn[0].imm will first sign-extend to 64bit -1 (0xffffffffFFFFFFFF) and then add 0x1FFFFFFFF, producing incorrect value 0xFFFFFFFF. The correct value should be 0x1FFFFFFFF. Changing insn[0].imm to __u32 first will prevent 64bit sign extension and fix the issue. Merging high and low 32bit values also changed from '+' to '|' to be consistent with other similar occurences in kernel and libbpf. Acked-by: Andrii Nakryiko Acked-by: Dave Marchevsky Signed-off-by: Yonghong Song --- tools/lib/bpf/relo_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c index 0dce5644877b..073a54ed7432 100644 --- a/tools/lib/bpf/relo_core.c +++ b/tools/lib/bpf/relo_core.c @@ -1027,7 +1027,7 @@ int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn, return -EINVAL; } - imm = insn[0].imm + ((__u64)insn[1].imm << 32); + imm = (__u32)insn[0].imm | ((__u64)insn[1].imm << 32); if (res->validate && imm != orig_val) { pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %llu -> %llu\n", prog_name, relo_idx,