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 95D99C433EF for ; Mon, 13 Jun 2022 14:26:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383395AbiFMO0N (ORCPT ); Mon, 13 Jun 2022 10:26:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1383641AbiFMOXl (ORCPT ); Mon, 13 Jun 2022 10:23:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B537C46CA8; Mon, 13 Jun 2022 04:44:41 -0700 (PDT) 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 CA737B80EA7; Mon, 13 Jun 2022 11:44:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3DB5AC34114; Mon, 13 Jun 2022 11:44:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655120678; bh=hmW26ierwBEx/09J/9XfPfU28+IK1f9jBl/K8WI4A9c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a8/vqJmrTUBjagCx3sGaV2T+ombDELF/5LjJRaYIr16LYnGHGoBzUNABc4pu34KiF Go3iwvomFBv1kLdVSffDvsHoac/zxLWgX43v6uF9w3WHwrLeAb41SC54k8KJ7ExEmr ycdGrvMk92KK0hEMWGY2OrpNhXhwA5ygxY7qmUAg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Menglong Dong , Daniel Borkmann , Jiang Biao , Hao Peng , Ilya Leoshkevich , Sasha Levin Subject: [PATCH 5.17 094/298] bpf: Fix probe read error in ___bpf_prog_run() Date: Mon, 13 Jun 2022 12:09:48 +0200 Message-Id: <20220613094927.800622133@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220613094924.913340374@linuxfoundation.org> References: <20220613094924.913340374@linuxfoundation.org> User-Agent: quilt/0.66 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: Menglong Dong [ Upstream commit caff1fa4118cec4dfd4336521ebd22a6408a1e3e ] I think there is something wrong with BPF_PROBE_MEM in ___bpf_prog_run() in big-endian machine. Let's make a test and see what will happen if we want to load a 'u16' with BPF_PROBE_MEM. Let's make the src value '0x0001', the value of dest register will become 0x0001000000000000, as the value will be loaded to the first 2 byte of DST with following code: bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off)); Obviously, the value in DST is not correct. In fact, we can compare BPF_PROBE_MEM with LDX_MEM_H: DST = *(SIZE *)(unsigned long) (SRC + insn->off); If the memory load is done by LDX_MEM_H, the value in DST will be 0x1 now. And I think this error results in the test case 'test_bpf_sk_storage_map' failing: test_bpf_sk_storage_map:PASS:bpf_iter_bpf_sk_storage_map__open_and_load 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:attach_iter 0 nsec test_bpf_sk_storage_map:PASS:create_iter 0 nsec test_bpf_sk_storage_map:PASS:read 0 nsec test_bpf_sk_storage_map:FAIL:ipv6_sk_count got 0 expected 3 $10/26 bpf_iter/bpf_sk_storage_map:FAIL The code of the test case is simply, it will load sk->sk_family to the register with BPF_PROBE_MEM and check if it is AF_INET6. With this patch, now the test case 'bpf_iter' can pass: $10 bpf_iter:OK Fixes: 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter") Signed-off-by: Menglong Dong Signed-off-by: Daniel Borkmann Reviewed-by: Jiang Biao Reviewed-by: Hao Peng Cc: Ilya Leoshkevich Link: https://lore.kernel.org/bpf/20220524021228.533216-1-imagedong@tencent.com Signed-off-by: Sasha Levin --- kernel/bpf/core.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 64c44eed8c07..10c4a2028e07 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1671,6 +1671,11 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) CONT; \ LDX_MEM_##SIZEOP: \ DST = *(SIZE *)(unsigned long) (SRC + insn->off); \ + CONT; \ + LDX_PROBE_MEM_##SIZEOP: \ + bpf_probe_read_kernel(&DST, sizeof(SIZE), \ + (const void *)(long) (SRC + insn->off)); \ + DST = *((SIZE *)&DST); \ CONT; LDST(B, u8) @@ -1678,15 +1683,6 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) LDST(W, u32) LDST(DW, u64) #undef LDST -#define LDX_PROBE(SIZEOP, SIZE) \ - LDX_PROBE_MEM_##SIZEOP: \ - bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off)); \ - CONT; - LDX_PROBE(B, 1) - LDX_PROBE(H, 2) - LDX_PROBE(W, 4) - LDX_PROBE(DW, 8) -#undef LDX_PROBE #define ATOMIC_ALU_OP(BOP, KOP) \ case BOP: \ -- 2.35.1