From nobody Sun Feb 8 05:28:25 2026 Received: from mail-qk1-f201.google.com (mail-qk1-f201.google.com [209.85.222.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5DE551FCFCE for ; Tue, 4 Mar 2025 21:40:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741124435; cv=none; b=Z/PflaFq4hnbR1R73xRaPYceiSgKuDZpJTv0x41140Ooca0gjOfkEC4Ed0dsL5nfoXlR512oFgVpl/w5Hu+Q33F5Rwlg4ThMcNKFIGWvsskNClmo5eGMBMJX69dSQZ4r0hdK9BZbmkXu/QRj4mjdp4fWZnK6z5tR1aRSOo0AiJk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741124435; c=relaxed/simple; bh=yMVc03CiFIe63aIIGzoNIlRXnzJld9erR9/9N+KScOc=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=LFW5bDjEd7G2oqShU0a6nMCZ/y4Ai8Sn3ggCaVvaB8wYr74UJq6I+e+wZVKM41r4ZCTfan2KIaw2BK9xuj8r3VF8E94I0lHjGY6gHhMeGaP7MaCq8Qx7tqXxIWmZNZLNdt8s6JF0pTGYq7nJIK11FveUBM53GagozTMknNabX8M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--zecheng.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=VvC2870b; arc=none smtp.client-ip=209.85.222.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--zecheng.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="VvC2870b" Received: by mail-qk1-f201.google.com with SMTP id af79cd13be357-7c0a3568f4eso689941285a.3 for ; Tue, 04 Mar 2025 13:40:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1741124433; x=1741729233; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=y3Km4ffsrY7Diu2crSx1d4N0oe7gpAjwafmNybMUZgc=; b=VvC2870bgBeMnuyt/xuFfaQoKz+QWKzc+44I3k7HkyYiPxKtSsUl4j+BiH5n7BJ9GC n/ycJaTGHSrsmM8kicu812T+n4m+Eh+lvc/ArzqZRfMC7lbjpURfTpYE+F3RrO8NkPuF 2Zu9aUdNs+UqUj9JmtyI+Ac31R5byxkrlbA1bH+MWtKgOWwnXopeEg58YxK0yTVTHt96 o0x68HSsa0rBLOURctrgFMnFuqMMk+geTPugqca2HeDgtz15pibyaTF5zVL+2X1Dftdk tn3feg3A46tPYP7CJwWFsfgJzCqopEOgA+PpHlYSJqVBjBa+zG/000HARNBWyZ9vpXhV cxqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741124433; x=1741729233; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=y3Km4ffsrY7Diu2crSx1d4N0oe7gpAjwafmNybMUZgc=; b=CS4gsSZjQI1ZCm8n++QyNrPd/Igm1a/e3XFC+RtSQq1aqkQoGILpz3H448nGwcpYdb 72h/tk7xifEdWePsCE5zjIALBDmB6feXl7+ZWr6xIRfoYYd1mBtNdWaJx4ZBo9RkSKH0 ZTSmmQre7UDa2f7qtZT+VffKtqDOwqZruFLEWRgmRJ87Z0rltVsM0ybXVAHNaxnjUbVH jvPgR3k/ox1wt723vRM+ouZKZiMGHlnGWTFj6ZQYGorc2RHU115q8CQ8goBFjyh6QTGY INYfAITvHeFY2VdYOnyPqil/jp/aDsT55GIAtjxJfdVb0oB7nifww59mT+jj+Q2zQnuw hPaQ== X-Forwarded-Encrypted: i=1; AJvYcCVoZ4wTQmgcRgHaBMwHi86ySU0CSqtytr2bK9vaSJ3TKNJ+XEOUCY51/RV922XifW2xZP4F71MIGvPnPZQ=@vger.kernel.org X-Gm-Message-State: AOJu0YwXGjZTCb0EO4g4TFcKJUvTM0uMTLM9MSbAjYSXI3pKfnFWOV1q zJzxCtkJLCEfq3V6vhIg8DkQgOqd9q6ChiLRpIWLkkU30+VyF75+UXOF2KpgcWZVBjx2uISDXZp kC4JHag== X-Google-Smtp-Source: AGHT+IHg+rNumrTbBj3/RSldd2K7p42fYL3Ul9QwVcltGLIJdffnwHo3ZEudeodZ5gouoH9ETTlNVHehpo/6 X-Received: from qknpb23.prod.google.com ([2002:a05:620a:8397:b0:7c3:d9b1:8227]) (user=zecheng job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:2625:b0:7c3:d63d:7bcd with SMTP id af79cd13be357-7c3d8e46660mr136259585a.41.1741124433219; Tue, 04 Mar 2025 13:40:33 -0800 (PST) Date: Tue, 4 Mar 2025 21:40:31 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250304214031.2882646-1-zecheng@google.com> Subject: [PATCH] sched/fair: Fix potential memory corruption in child_cfs_rq_on_list From: Zecheng Li To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Cc: Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Josh Don , linux-kernel@vger.kernel.org, Zecheng Li Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" child_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq. This 'prev' pointer can originate from struct rq's leaf_cfs_rq_list, making the conversion invalid and potentially leading to memory corruption. Depending on the relative positions of leaf_cfs_rq_list and the task group (tg) pointer within the struct, this can cause a memory fault or access garbage data. The issue arises in list_add_leaf_cfs_rq, where both cfs_rq->leaf_cfs_rq_list and rq->leaf_cfs_rq_list are added to the same leaf list. Also, rq->tmp_alone_branch can be set to rq->leaf_cfs_rq_list. This adds a check `if (prev =3D=3D &rq->leaf_cfs_rq_list)` after the main conditional in child_cfs_rq_on_list. This ensures that the container_of operation will convert a correct cfs_rq struct. This check is sufficient because only cfs_rqs on the same CPU are added to the list, so verifying the 'prev' pointer against the current rq's list head is enough. Fixes a potential memory corruption issue that due to current struct layout might not be manifesting as a crash but could lead to unpredictable behavior when the layout changes. Signed-off-by: Zecheng Li Reviewed-by: Vincent Guittot --- kernel/sched/fair.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 857808da23d8..9dafb374d76d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4061,15 +4061,17 @@ static inline bool child_cfs_rq_on_list(struct cfs_= rq *cfs_rq) { struct cfs_rq *prev_cfs_rq; struct list_head *prev; + struct rq *rq =3D rq_of(cfs_rq); =20 if (cfs_rq->on_list) { prev =3D cfs_rq->leaf_cfs_rq_list.prev; } else { - struct rq *rq =3D rq_of(cfs_rq); - prev =3D rq->tmp_alone_branch; } =20 + if (prev =3D=3D &rq->leaf_cfs_rq_list) + return false; + prev_cfs_rq =3D container_of(prev, struct cfs_rq, leaf_cfs_rq_list); =20 return (prev_cfs_rq->tg->parent =3D=3D cfs_rq->tg); base-commit: 7ab02bd36eb444654183ad6c5b15211ddfa32a8f --=20 2.48.1