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 X-Spam-Level: X-Spam-Status: No, score=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 6111FC433F5 for ; Mon, 20 Sep 2021 17:09:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BADD61B7F for ; Mon, 20 Sep 2021 17:09:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345397AbhITRKn (ORCPT ); Mon, 20 Sep 2021 13:10:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:59366 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238404AbhITRH4 (ORCPT ); Mon, 20 Sep 2021 13:07:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 298EE61205; Mon, 20 Sep 2021 16:55:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632156952; bh=Agg3vYpoBwOvnbNhr7OJidNa9a79zLnmyMSVN8MkVqE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gO3b4bl4rDNUt8rDLzC/APB2zoQrmDr0N6kuqk7ouAiZgNnjHGeprXTLbBp020hDO DwK5YcOP/Ur1KZ8LXUMvL6iQUDnGIVMw2a0EZGQ9sHK/w5KGM7A6ltHdWbN5vP1I3T 2eZ+PBhzwyWb7cppVz2LtOJ2vHmSHp/nY+u4BNFc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Baptiste Lepers , "Peter Zijlstra (Intel)" Subject: [PATCH 4.9 161/175] events: Reuse value read using READ_ONCE instead of re-reading it Date: Mon, 20 Sep 2021 18:43:30 +0200 Message-Id: <20210920163923.332064010@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163918.068823680@linuxfoundation.org> References: <20210920163918.068823680@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: linux-kernel@vger.kernel.org From: Baptiste Lepers commit b89a05b21f46150ac10a962aa50109250b56b03b upstream. In perf_event_addr_filters_apply, the task associated with the event (event->ctx->task) is read using READ_ONCE at the beginning of the function, checked, and then re-read from event->ctx->task, voiding all guarantees of the checks. Reuse the value that was read by READ_ONCE to ensure the consistency of the task struct throughout the function. Fixes: 375637bc52495 ("perf/core: Introduce address range filtering") Signed-off-by: Baptiste Lepers Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210906015310.12802-1-baptiste.lepers@gmail.com Signed-off-by: Greg Kroah-Hartman --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8115,7 +8115,7 @@ static void perf_event_addr_filters_appl if (task == TASK_TOMBSTONE) return; - mm = get_task_mm(event->ctx->task); + mm = get_task_mm(task); if (!mm) goto restart;