From nobody Tue Jun 30 11:09:17 2026 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 3E034C433F5 for ; Wed, 19 Jan 2022 01:24:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350706AbiASBYo (ORCPT ); Tue, 18 Jan 2022 20:24:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350658AbiASBYn (ORCPT ); Tue, 18 Jan 2022 20:24:43 -0500 Received: from mail-pf1-x42c.google.com (mail-pf1-x42c.google.com [IPv6:2607:f8b0:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D9C6C06161C for ; Tue, 18 Jan 2022 17:24:43 -0800 (PST) Received: by mail-pf1-x42c.google.com with SMTP id q25so994226pfl.8 for ; Tue, 18 Jan 2022 17:24:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=p9a1D5pmV4meg6CQGuPluc6XFagCjYKD6drtbQ058cc=; b=zfArFxPdbwEvo40qrJXBnsNwMXTNDZwXC2MSacfoZ4aSq6lFZOfDPxz18fpOf5Rkti HGGvWYmYlMtPRNG6SJ//QpqCYAI6J/Af24z4QC3+P61rKfEXS7Bawc8yLlRmHnZKHB4x nPuX/YNLPJnw8M4t2W2GRvbS+8ws65xigUtoxPG06gwCds0RPvBmyOVS+I8SLJcyuKmw edTP3xBACEoV/TIrZryl9Zkjnajd/7DCmBELv2ECPru3ilEELaoN0fmBMM03ERHHy87s VRVOU8nUOr5231HIsSKkOYJXGqJ0wFfpTQvvq4TOIgc8kNIFr3iqKP1h9JORnRCsZmu2 UgwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=p9a1D5pmV4meg6CQGuPluc6XFagCjYKD6drtbQ058cc=; b=X6WLQ1Z0nHrnil0+1VMz5SgoxLi7pHgjYn5xpUZqywmJnaDtmBpYTuJXrnTuxT9v9d 2kXO2SETMa6Co/ozWqPLE3LfJWslnoKqGyCzMx2NQF5xTJ31bRYqCbmRIK2Y4+Zz6YzH RDiAxJaFNmKF8KEMOnfYW49wWKCAMGkYP2EklFmtm7h4DrPW/z0e2yT1oFhvVyBqp04X xGac38eQElrnd5PQoA34UU04G4Rl1dOoEGlCS+4PtfriMWZ6tbf68gJQ+MRAPOgEMbGG LESz32sNmD2PwkDw5tmht37dvIp0fuS8MakC43PlUG8sCAz5F5Ed5wnzTlKhU3lkwGkP PK8Q== X-Gm-Message-State: AOAM533yPN49+AMbhJhVzmc1Ij4CZ5w/pDonVSCKizLSKdLl5j3/XxuT IXcykVXRM+Mpi0ThR3vTLsBr2g== X-Google-Smtp-Source: ABdhPJzvszrBUj/mnxzS+wYrDiuF+IkE//2Tc3hRguE0N5ir5EI2ke7KCjVgQq6C3nHfdjLonSh3+w== X-Received: by 2002:a62:1b44:0:b0:4be:3d88:ea9c with SMTP id b65-20020a621b44000000b004be3d88ea9cmr28376548pfb.56.1642555482726; Tue, 18 Jan 2022 17:24:42 -0800 (PST) Received: from localhost.localdomain ([50.39.160.154]) by smtp.gmail.com with ESMTPSA id ip2sm3820487pjb.11.2022.01.18.17.24.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Jan 2022 17:24:42 -0800 (PST) From: Tadeusz Struk To: mingo@redhat.com Cc: Tadeusz Struk , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Zhang Qiao , stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] sched/fair: Fix fault in reweight_entity Date: Tue, 18 Jan 2022 17:24:17 -0800 Message-Id: <20220119012417.299060-1-tadeusz.struk@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Syzbot found a GPF in reweight_entity. This has been bisected to commit c85c6fadbef0 ("kernel/sched: Fix sched_fork() access an invalid sched_task_= group") Looks like after this change there is a time window, when task_struct->se.cfs_rq can be NULL. This can be exploited to trigger null-ptr-deref by calling setpriority on that task. Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Steven Rostedt Cc: Ben Segall Cc: Mel Gorman Cc: Daniel Bristot de Oliveira Cc: Zhang Qiao Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Link: https://syzkaller.appspot.com/bug?id=3D9d9c27adc674e3a7932b22b61c79a0= 2da82cbdc1 Fixes: c85c6fadbef0 ("kernel/sched: Fix sched_fork() access an invalid sche= d_task_group") Signed-off-by: Tadeusz Struk --- kernel/sched/fair.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 095b0aa378df..196f8cee3f9b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3042,6 +3042,9 @@ dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_= entity *se) { } static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, unsigned long weight) { + if (!cfs_rq) + return; + if (se->on_rq) { /* commit outstanding execution time */ if (cfs_rq->curr =3D=3D se) --=20 2.34.1