From nobody Tue Sep 29 13:20:15 2026 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00BB5474277 for ; Fri, 7 Aug 2026 12:58:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786107504; cv=none; b=Ah1gemQIrMvv2wyZCppjWP/8Rc8BzrzVKBIF+SGiQ/PSczOeTBGhJrxjFBHN9WYdC/MSu+b+yhAV9iRZHsUjHxhaRQ0rgRWbCxqLxY91tKcdJ07zSJ1/hDVRODoIAXZNIC/e6cxEhUcl0l08/Xg0P8q5iOYLU160XQ8kbI30lJk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786107504; c=relaxed/simple; bh=Y9/aekxWQuoAMUmR6BdZp3iMVUakfDh7O5ktnd+DwPs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=X0QiRrmASSmEYB0qHQBtxoA82HlBqQierv4e5uT6mNQXprp/HjhmyYIHz2Qg2TEEahCDoTllr7wFNdq09HIUC7cd9Zx+BV2KEWjDhGKl+le6Pp3tnjq0RFY3dL1bBQZmtE2L6sOCwGstNrQxCgEj+WEk3WyoK7b7OzLQsBzCw74= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=YpXNasDB; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="YpXNasDB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=4Y cHFwfxuPptEHniUxgvrZUbdZPNkJGiJoN2Tgxz3Bk=; b=YpXNasDBGwg7DiErIY IyE7rkHbG8U0VJEo2r1O1/lgO1gtdap9FKtdzGwzswgDCi5MGtC7FnJeV/1WLFM7 spwBXuicnGjwsa4oV4aS0PHmw/D88CzNBlYWe6nKAsn/PHeQAX4XgstGqqarQQko GluO+eD7gAJ1SNwAtv0gOZRLg= Received: from cuijian-virtual-machine.localdomain (unknown []) by gzsmtp2 (Coremail) with SMTP id PSgvCgCHGwAt1nVqgcHtKA--.4340S2; Fri, 07 Aug 2026 20:57:18 +0800 (CST) From: Cui Jian To: Zhan Xusheng Cc: Tejun Heo , David Vernet , Andrea Righi , Changwoo Min , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, Cui Jian Subject: [PATCH] sched_ext: Add NULL check in find_parent_sched() Date: Fri, 7 Aug 2026 20:57:16 +0800 Message-Id: <20260807125716.56531-1-cjian720@163.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260807114534.1253158-1-zhanxusheng@xiaomi.com> References: <20260807114534.1253158-1-zhanxusheng@xiaomi.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: PSgvCgCHGwAt1nVqgcHtKA--.4340S2 X-Coremail-Antispam: 1Uf129KBjvdXoW7GrykXr1xWw13JrW7Kw45ZFb_yoW3tFb_Zw sxGF1UG34UCr1DKw17Cw4fXryrKFW8WF95ZF9rKFZ8JF18JrZIqrn5CF95trnxKayIvF98 Cr9FqF98Cwn7CjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7sRibyCDUUUUU== X-CM-SenderInfo: pfmlt0qxsqqiywtou0bp/xtbC+A64RWp11i6GDQAA3n Content-Type: text/plain; charset="utf-8" find_parent_sched() dereferences cgrp->scx_sched without checking for NULL. This is safe in practice because scx_sched is always set for cgroups that can reach this function, but add a defensive check for robustness. Signed-off-by: Cui Jian --- kernel/sched/ext/sub.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c index d7842a609d96..6395281bae71 100644 --- a/kernel/sched/ext/sub.c +++ b/kernel/sched/ext/sub.c @@ -1209,6 +1209,10 @@ static struct scx_sched *find_parent_sched(struct cg= roup *cgrp) =20 lockdep_assert_held(&scx_sched_lock); =20 + /* no SCX sched */ + if (!parent) + return ERR_PTR(-ENODEV); + /* can't attach twice to the same cgroup */ if (parent->cgrp =3D=3D cgrp) return ERR_PTR(-EBUSY); --=20 2.34.1