From nobody Sun Dec 28 04:47:43 2025 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 0185FC4167D for ; Tue, 12 Dec 2023 22:23:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377824AbjLLWXd (ORCPT ); Tue, 12 Dec 2023 17:23:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377804AbjLLWXa (ORCPT ); Tue, 12 Dec 2023 17:23:30 -0500 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 797BEA1; Tue, 12 Dec 2023 14:23:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1702419817; x=1733955817; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=ozp3JOHCZkR8rjYbeX9k9xgnEnDFYEFFgWgRZ7ytBZk=; b=KSICwt3GnwIiqUgmtr/pYFf0phdUHXZ3smRgJ4nL9UjDBFMUNDhmCmmD 2SDxQ7fKphsoE7bKvENIQlYIcf536dnMbf78/I9MKBj+LcNTWmodcj4yi Nwh/YFEbPxtb6eIEllAztlTSWSZvj3/9io2RD+/a+PLOsdgtylg619H2A QUhSUQR6LblPrNOKeA8OSyH6YAgE7FJS+ltrxtK8ZsGnwXl7XZwFkFWXu 7/K8IEGdmn0bx9HEqPXKpofnxAb7anCrbi1ZqTILCIp1432HwLVtzG2s1 l96z/E5G6j2w7bW4EkGtYOwRf+Phbc4XTJkpD0hFn4RDctRvg8zx7s30F g==; X-IronPort-AV: E=McAfee;i="6600,9927,10922"; a="2049303" X-IronPort-AV: E=Sophos;i="6.04,271,1695711600"; d="scan'208";a="2049303" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2023 14:23:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10922"; a="802631185" X-IronPort-AV: E=Sophos;i="6.04,271,1695711600"; d="scan'208";a="802631185" Received: from ranerica-svr.sc.intel.com ([172.25.110.23]) by orsmga008.jf.intel.com with ESMTP; 12 Dec 2023 14:23:35 -0800 From: Ricardo Neri To: x86@kernel.org Cc: Andreas Herrmann , Catalin Marinas , Chen Yu , Len Brown , Radu Rendec , Pierre Gondois , Pu Wen , "Rafael J. Wysocki" , Sudeep Holla , Srinivas Pandruvada , Will Deacon , Zhang Rui , Huang Ying , "Ravi V. Shankar" , stable@vger.kernel.org, linux-kernel@vger.kernel.org, Ricardo Neri , linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 1/4] cacheinfo: Check for null last-level cache info Date: Tue, 12 Dec 2023 14:25:16 -0800 Message-Id: <20231212222519.12834-2-ricardo.neri-calderon@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20231212222519.12834-1-ricardo.neri-calderon@linux.intel.com> References: <20231212222519.12834-1-ricardo.neri-calderon@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Before determining the validity of the last-level cache info, ensure that it has been allocated. Simply checking for non-zero cache_leaves() is not sufficient, as some architectures (e.g., Intel processors) have non-zero cache_leaves() before allocation. Dereferencing NULL cacheinfo can occur in update_per_cpu_data_slice_size(). This function iterates over all online CPUs. However, a CPU may have come online recently, but its cacheinfo may not have been allocated yet. Cc: Andreas Herrmann Cc: Catalin Marinas Cc: Chen Yu Cc: Huang Ying Cc: Len Brown Cc: Radu Rendec Cc: Pierre Gondois Cc: Pu Wen Cc: "Rafael J. Wysocki" Cc: Sudeep Holla Cc: Srinivas Pandruvada Cc: Will Deacon Cc: Zhang Rui Cc: linux-arm-kernel@lists.infradead.org Cc: stable@vger.kernel.org Signed-off-by: Ricardo Neri Reviewed-by: Sudeep Holla --- Changes since v3: * Introduced this patch. Changes since v2: * N/A Changes since v1: * N/A --- The dereference of a NULL cacheinfo is not observed today because cache_leaves(cpu) is zero until after init_cache_level() is called (during the CPU hotplug callback). A subsequent changeset will set the number of cache leaves earlier and the NULL-pointer dereference will be observed. --- drivers/base/cacheinfo.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c index f1e79263fe61..967c5cf3fb1d 100644 --- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -61,6 +61,9 @@ bool last_level_cache_is_valid(unsigned int cpu) if (!cache_leaves(cpu)) return false; =20 + if (!per_cpu_cacheinfo(cpu)) + return false; + llc =3D per_cpu_cacheinfo_idx(cpu, cache_leaves(cpu) - 1); =20 return (llc->attributes & CACHE_ID) || !!llc->fw_token; --=20 2.25.1