From patchwork Tue Sep 29 22:50:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 11807331 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8CD246CB for ; Tue, 29 Sep 2020 22:50:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5FB1C207C4 for ; Tue, 29 Sep 2020 22:50:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="N+QCM+e8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728384AbgI2WuZ (ORCPT ); Tue, 29 Sep 2020 18:50:25 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:53670 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728192AbgI2WuY (ORCPT ); Tue, 29 Sep 2020 18:50:24 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 08TMo9l2019370 for ; Tue, 29 Sep 2020 15:50:24 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=yeIlLcPVe73ANCroUFPRO6l+RyUYuFYQQpuTnrOuYEs=; b=N+QCM+e8S36WAu7lubtYsPf6iR+s9EONLOsRK36e1L7ucqijHV4dNPCm4lyk+ZLbc2v4 tU4bzQiEScKNPaWgXgzLWfiqxQZeKjSyRi55MDjnOnVAAFfzYT45aByhqsoZJQKGK//a neDQsp5icMDqA76s7MWWEnke51OG9TwM1jM= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 33v6v42hc4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 29 Sep 2020 15:50:24 -0700 Received: from intmgw003.08.frc2.facebook.com (2620:10d:c085:108::8) by mail.thefacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 29 Sep 2020 15:50:23 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 71E5B62E56DB; Tue, 29 Sep 2020 15:50:22 -0700 (PDT) From: Song Liu To: , CC: , , , , , Song Liu Subject: [PATCH bpf-next] bpf: fix raw_tp test run in preempt kernel Date: Tue, 29 Sep 2020 15:50:13 -0700 Message-ID: <20200929225013.930-1-songliubraving@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-29_14:2020-09-29,2020-09-29 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 malwarescore=0 mlxscore=0 impostorscore=0 spamscore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 mlxlogscore=768 phishscore=0 suspectscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009290194 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org In preempt kernel, BPF_PROG_TEST_RUN on raw_tp triggers: [ 35.874974] BUG: using smp_processor_id() in preemptible [00000000] code: new_name/87 [ 35.893983] caller is bpf_prog_test_run_raw_tp+0xd4/0x1b0 [ 35.900124] CPU: 1 PID: 87 Comm: new_name Not tainted 5.9.0-rc6-g615bd02bf #1 [ 35.907358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 35.916941] Call Trace: [ 35.919660] dump_stack+0x77/0x9b [ 35.923273] check_preemption_disabled+0xb4/0xc0 [ 35.928376] bpf_prog_test_run_raw_tp+0xd4/0x1b0 [ 35.933872] ? selinux_bpf+0xd/0x70 [ 35.937532] __do_sys_bpf+0x6bb/0x21e0 [ 35.941570] ? find_held_lock+0x2d/0x90 [ 35.945687] ? vfs_write+0x150/0x220 [ 35.949586] do_syscall_64+0x2d/0x40 [ 35.953443] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by calling migrate_disable() before smp_processor_id(). Fixes: 1b4d60ec162f ("bpf: Enable BPF_PROG_TEST_RUN for raw_tracepoint") Reported-by: Alexei Starovoitov Signed-off-by: Song Liu --- net/bpf/test_run.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index fde5db93507c4..3ea05a5daf544 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -251,11 +251,7 @@ __bpf_prog_test_run_raw_tp(void *data) { struct bpf_raw_tp_test_run_info *info = data; - rcu_read_lock(); - migrate_disable(); info->retval = BPF_PROG_RUN(info->prog, info->ctx); - migrate_enable(); - rcu_read_unlock(); } int bpf_prog_test_run_raw_tp(struct bpf_prog *prog, @@ -293,27 +289,27 @@ int bpf_prog_test_run_raw_tp(struct bpf_prog *prog, info.prog = prog; + rcu_read_lock(); + migrate_disable(); if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 || cpu == smp_processor_id()) { __bpf_prog_test_run_raw_tp(&info); - } else { + } else if (cpu >= nr_cpu_ids || !cpu_online(cpu)) { /* smp_call_function_single() also checks cpu_online() * after csd_lock(). However, since cpu is from user * space, let's do an extra quick check to filter out * invalid value before smp_call_function_single(). */ - if (cpu >= nr_cpu_ids || !cpu_online(cpu)) { err = -ENXIO; - goto out; - } - + } else { err = smp_call_function_single(cpu, __bpf_prog_test_run_raw_tp, &info, 1); - if (err) - goto out; } + migrate_enable(); + rcu_read_unlock(); - if (copy_to_user(&uattr->test.retval, &info.retval, sizeof(u32))) + if (err == 0 && + copy_to_user(&uattr->test.retval, &info.retval, sizeof(u32))) err = -EFAULT; out: