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=-26.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 5ED30C433ED for ; Fri, 30 Apr 2021 15:14:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12AA361456 for ; Fri, 30 Apr 2021 15:14:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230386AbhD3PPG (ORCPT ); Fri, 30 Apr 2021 11:15:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229759AbhD3PPG (ORCPT ); Fri, 30 Apr 2021 11:15:06 -0400 Received: from mail-wm1-x349.google.com (mail-wm1-x349.google.com [IPv6:2a00:1450:4864:20::349]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD1AAC06174A for ; Fri, 30 Apr 2021 08:14:17 -0700 (PDT) Received: by mail-wm1-x349.google.com with SMTP id b16-20020a7bc2500000b029014587f5376dso2100922wmj.1 for ; Fri, 30 Apr 2021 08:14:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=R9A0FFHMxGak+rogDjXG1194mPgT82uPpYtaWutuk44=; b=bF9llhs8keQZLeZb1rULfFR6RXdo3OGXFzcD46QMcHJEq+mENPol5dgQ5zpDTV5LFY b+TdIt8ntPz6+hU7Wp7V9gAWsAiyuU4sq5G8qs67J+X/K0El2v73irFtdC8glrIEs0w7 gaG3SijwVaKyZ5TIzrKTeXrRxzpd0mjM5PCg8ZOYMpjbAp7sp3+Sf9ujKJl8FZeTwSks iUma/Kxg0z/KxwGsLiuEMd/K3KkzrJ/LWniV5XDPdfsujuXGzr2xUHb6sDRaXj+9JQ/d Fqw6IoliXH35GwonqJiFCm+S16XVDL6JVJ2eqMhwXA6vgIp/MPMmHMyamh9GZfaUf6bh enYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=R9A0FFHMxGak+rogDjXG1194mPgT82uPpYtaWutuk44=; b=PTefsjxEGlBqQe8r3nqusFzRs/e7Nwc/p6RxGBuL5zw5lGmSF56SvP0ey6jbViwOsY mevMLrx58L8qIOWoY3C+gEk1R2Vee8Pa1+ZMW5nv3GKr5OSztCOHyNfBTZT/QPEC2itb IekngHQsfiIeLugfaz+MKyrAM88GK2fXvbUSNtPg/mMFfOsuAFX4UEhdmajWHwh85fs9 fI0kzCjdz7YITOQ2FhiaPaQLJKw3/kxJHiYYPqW3ONCiAYquqT6i0OIlYQIa2bB01tEZ pAv1p0d3pe9ednYLptoF+o+ubGbtIfi3BKKLgoZcv/xgKHsTIhTXhlgZ6e36bizOuZm4 FjbA== X-Gm-Message-State: AOAM533501LXmVdKJb5dWfdfvsiJw8bq5Q48NUjjZHikGLnzWWZL2Isg VrxzbagpVffBw3l6euVlSchqDyOaUhMG X-Google-Smtp-Source: ABdhPJzWzEBxQ/TkaFJYFuwSAds1UbCagbUIle41a6jkUMcfZUkYazylW1NQvr0dh2YPOrQUoHQgW7bzX2jQ X-Received: from r2d2-qp.c.googlers.com ([fda3:e722:ac3:10:28:9cb1:c0a8:1652]) (user=qperret job=sendgmr) by 2002:a1c:540b:: with SMTP id i11mr17201265wmb.40.1619795656278; Fri, 30 Apr 2021 08:14:16 -0700 (PDT) Date: Fri, 30 Apr 2021 15:14:12 +0000 Message-Id: <20210430151412.160913-1-qperret@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.31.1.527.g47e6f16901-goog Subject: [PATCH v3] sched: Fix out-of-bound access in uclamp From: Quentin Perret To: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, juri.lelli@redhat.com Cc: dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, qais.yousef@arm.com, kernel-team@android.com, linux-kernel@vger.kernel.org, patrick.bellasi@matbug.net Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Util-clamp places tasks in different buckets based on their clamp values for performance reasons. However, the size of buckets is currently computed using a rounding division, which can lead to an off-by-one error in some configurations. For instance, with 20 buckets, the bucket size will be 1024/20=51. A task with a clamp of 1024 will be mapped to bucket id 1024/51=20. Sadly, correct indexes are in range [0,19], hence leading to an out of bound memory access. Clamp the bucket id to fix the issue. Fixes: 69842cba9ace ("sched/uclamp: Add CPU's clamp buckets refcounting") Suggested-by: Qais Yousef Signed-off-by: Quentin Perret --- Changes in v3: - Keep rounding div to improve fairness (Vincent) --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 98191218d891..c12ec648423e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -928,7 +928,7 @@ DEFINE_STATIC_KEY_FALSE(sched_uclamp_used); static inline unsigned int uclamp_bucket_id(unsigned int clamp_value) { - return clamp_value / UCLAMP_BUCKET_DELTA; + return min_t(unsigned int, clamp_value / UCLAMP_BUCKET_DELTA, UCLAMP_BUCKETS - 1); } static inline unsigned int uclamp_none(enum uclamp_id clamp_id) -- 2.31.1.527.g47e6f16901-goog