From patchwork Thu Feb 18 00:16:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Cong Wang X-Patchwork-Id: 384239 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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, 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 C3457C433E6 for ; Thu, 18 Feb 2021 00:17:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 841D964DEC for ; Thu, 18 Feb 2021 00:17:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229889AbhBRARm (ORCPT ); Wed, 17 Feb 2021 19:17:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229708AbhBRARk (ORCPT ); Wed, 17 Feb 2021 19:17:40 -0500 Received: from mail-ot1-x32f.google.com (mail-ot1-x32f.google.com [IPv6:2607:f8b0:4864:20::32f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A433C061574; Wed, 17 Feb 2021 16:16:59 -0800 (PST) Received: by mail-ot1-x32f.google.com with SMTP id q4so345892otm.9; Wed, 17 Feb 2021 16:16:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=VmEI9bK6S+MA6iIG56tLhKiAJVbLpfqcE1mPZiBV0Dk=; b=UjVV4Uxj2xDfn/Pw9giP4UOdGVOyMe0l1DhcV3wK5RGp+LeVro/jzvuNKPwROutpfk wxErXWYLFm9LFmatrMQgW3PdTXFx+ItE/9SqXmhZFKa7a2XZ+Z+czHM1jz4BKt6Qbf51 yhKKfQROnxt28QiCZVZzdaws7l+cuEud/OZ57rzQnLDGF8q1dWLWNkv10qychI5Hwx3y wlxiX5EakQX2HQXvM3xaq+tAgRlq8RlTmhfMJzzSyHcBHw3LKJ9Lbn3dVrRJvt1PNTBp ayq+7tp8aU8Pap9qHycyK1N7RPdmTseDrb9DzgtNLNC3YpdbzWfk+9CQW0pRppRH8nA/ dqmQ== 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:mime-version :content-transfer-encoding; bh=VmEI9bK6S+MA6iIG56tLhKiAJVbLpfqcE1mPZiBV0Dk=; b=cCdCBHpbsnvnzMWMBd+WoXTG49civQBDe2MpWgzzgDS6hdRAMBVT8SCtkcQms+ZSUP ooTuMwC1bp+itEc7H5//5X5tttwDeJvl15RbY7GKolQu8XCupkK87sY5XiuqMuW1M4p+ i9lidNXRiIe+7xfKCkbCEMbA271H5uIHoXbNtnH4iS2oo36zkEaZyRSvbmFuvVqSgXJa nL5AUSHT+t3CufmjN2wI9QgRq0nSCu+yckbx16nMEnxeQESuMdU8a+IroOF8uI9SGPci 9ymJF5c3Jb8Yj4EKV+yFrdcwIlZfSvsevX9trx1HYS24h7EEPVj2F+OU34pbio/AGOp1 X+lA== X-Gm-Message-State: AOAM531DsSFvH5Uyye+QlM3L+CcbekQUbsVEAsM2XJyB+0YU74nj2fCd 7E00YI5KSHXWBx2Hdou9JOFPql4My5lW6w== X-Google-Smtp-Source: ABdhPJyTKfJUTD1VslGvUiET3tWsD0LDfHYPn+dV7jul5SByRxcXtAeKaVhS+vLI3x7GmYTGy2QucA== X-Received: by 2002:a9d:58ca:: with SMTP id s10mr1173586oth.70.1613607417934; Wed, 17 Feb 2021 16:16:57 -0800 (PST) Received: from unknown.attlocal.net ([2600:1700:65a0:ab60:1d72:18:7c76:92e4]) by smtp.gmail.com with ESMTPSA id r205sm807458oib.15.2021.02.17.16.16.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Feb 2021 16:16:57 -0800 (PST) From: Cong Wang To: netdev@vger.kernel.org Cc: bpf@vger.kernel.org, Cong Wang , Jiang Wang , Alexei Starovoitov , Daniel Borkmann Subject: [Patch bpf-next v2] bpf: clear percpu pointers in bpf_prog_clone_free() Date: Wed, 17 Feb 2021 16:16:47 -0800 Message-Id: <20210218001647.71631-1-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Cong Wang Similar to bpf_prog_realloc(), bpf_prog_clone_create() also copies the percpu pointers, but the clone still shares them with the original prog, so we have to clear these two percpu pointers in bpf_prog_clone_free(). Otherwise we would get a double free: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 13 PID: 8140 Comm: kworker/13:247 Kdump: loaded Tainted: G                W    OE   5.11.0-rc4.bm.1-amd64+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 test_bpf: #1 TXA Workqueue: events bpf_prog_free_deferred RIP: 0010:percpu_ref_get_many.constprop.97+0x42/0xf0 Code: [...] RSP: 0018:ffffa6bce1f9bda0 EFLAGS: 00010002 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 00000000021dfc7b RDX: ffffffffae2eeb90 RSI: 867f92637e338da5 RDI: 0000000000000046 RBP: ffffa6bce1f9bda8 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000046 R11: 0000000000000000 R12: 0000000000000280 R13: 0000000000000000 R14: 0000000000000000 R15: ffff9b5f3ffdedc0 FS:    0000000000000000(0000) GS:ffff9b5f2fb40000(0000) knlGS:0000000000000000 CS:    0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000027c36c002 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace:     refill_obj_stock+0x5e/0xd0     free_percpu+0xee/0x550     __bpf_prog_free+0x4d/0x60     process_one_work+0x26a/0x590     worker_thread+0x3c/0x390     ? process_one_work+0x590/0x590     kthread+0x130/0x150     ? kthread_park+0x80/0x80     ret_from_fork+0x1f/0x30 This bug is 100% reproducible with test_kmod.sh. Reported-by: Jiang Wang Fixes: 700d4796ef59 ("bpf: Optimize program stats") Fixes: ca06f55b9002 ("bpf: Add per-program recursion prevention mechanism") Cc: Alexei Starovoitov Cc: Daniel Borkmann Signed-off-by: Cong Wang --- kernel/bpf/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 0ae015ad1e05..aa1e64196d8d 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1118,6 +1118,8 @@ static void bpf_prog_clone_free(struct bpf_prog *fp) * clone is guaranteed to not be locked. */ fp->aux = NULL; + fp->stats = NULL; + fp->active = NULL; __bpf_prog_free(fp); }