From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AFAE438C2CA; Mon, 23 Mar 2026 14:43:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774277030; cv=none; b=cWvbW+3/IMmobqI4IMP2QyUHTuJV84w/01Oqrh8PUO/HO9d5ji7iusIksV3cjrr4bmEiU8yRmDm7xGexiDlX3oiRUQlv8nLgL5niIg5DRHRHpriAWQtqEb012w98YuH7UypFnfXFtuWNg9I+26+9AfhGCEknbmedTlWCWg/kHpM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774277030; c=relaxed/simple; bh=xvhPYug+fHnpkMKd5UMVyXxPuwPWgReJQO9RfH28ukg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MA3RgAQDE+eyAkEsJQ/1ScwawqihI6LCrOV4yd2HKpSIbTAI2VTs3BaDzo8Op62DWbDtmuYWxkMSGaYcvAIbYVzq3WsVkox6l4RmwvD0rN6riOaUZOcquzagcKvSX4C8mMVVJP0VTXWuMzPNYRoSv60eQbI/WGM9EQjHNfariXQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zZ8Vc1K3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="zZ8Vc1K3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47CF6C4CEF7; Mon, 23 Mar 2026 14:43:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774277030; bh=xvhPYug+fHnpkMKd5UMVyXxPuwPWgReJQO9RfH28ukg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zZ8Vc1K35rEyO2uK+1y/uYf5vNAanPyK7CuZhdMtBzdHXOHIjc+OnQaQNvTBbDABt /CeVWFAO/SfgHe69m9xlSGtf9o8CDGUVY4RYxwydbd4IAWMEaW8JHwy01QKMvMtNiE mC7uoqI3rgKQ+AdZwrklvdqLAazOuVYZ0/vymsg0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Cheng-Yang Chou , Andrea Righi , Tejun Heo Subject: [PATCH 6.12 296/460] sched_ext: Remove redundant css_put() in scx_cgroup_init() Date: Mon, 23 Mar 2026 14:44:52 +0100 Message-ID: <20260323134533.758864579@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134526.647552166@linuxfoundation.org> References: <20260323134526.647552166@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cheng-Yang Chou commit 1336b579f6079fb8520be03624fcd9ba443c930b upstream. The iterator css_for_each_descendant_pre() walks the cgroup hierarchy under cgroup_lock(). It does not increment the reference counts on yielded css structs. According to the cgroup documentation, css_put() should only be used to release a reference obtained via css_get() or css_tryget_online(). Since the iterator does not use either of these to acquire a reference, calling css_put() in the error path of scx_cgroup_init() causes a refcount underflow. Remove the unbalanced css_put() to prevent a potential Use-After-Free (UAF) vulnerability. Fixes: 819513666966 ("sched_ext: Add cgroup support") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Cheng-Yang Chou Reviewed-by: Andrea Righi Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/sched/ext.c | 1 - 1 file changed, 1 deletion(-) --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4319,7 +4319,6 @@ static int scx_cgroup_init(void) ret = SCX_CALL_OP_RET(SCX_KF_UNLOCKED, cgroup_init, css->cgroup, &args); if (ret) { - css_put(css); scx_ops_error("ops.cgroup_init() failed (%d)", ret); return ret; }