From nobody Fri Dec 19 15:19:31 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.16]) (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 6BAFD4C92 for ; Tue, 27 Aug 2024 05:09:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724735381; cv=none; b=TaL1iW2AbpVM1Nxi3OgkirHbF0PjyJQAwOBEQDHswt4ffJ0L2SWt1Mcr0NH/IZ6KVwfXxBICsvJQAeqTDxBifTjhKdOljpPqnrY3HGFy98Pji/VpVsd7qAzXUatO6W1E6btCVMyDjRJOEl77xFmk7BR9xmtI9EqAz2x66Ba+2dk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724735381; c=relaxed/simple; bh=CIvKikOPhEGLHf7EWowVUA0K+rreGMGnHAgAKNeRrJk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=OPlmq6bbSxlVK8ktKJKOTCJogK3ocAzN+z1iJEGLSuXHK3BY8GgfwhH9aYG81yX79MI99Pt8Fh72MGXjx7KmNGCaNquH/mj7FjtQ9KynmmxEC2S9kBgU7xeA8d58QjtgW+o30+xorBicPfo9mlKMgOJksQRmaGkx7w9vXWCs7pU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=ftlakTUv; arc=none smtp.client-ip=192.198.163.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="ftlakTUv" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1724735380; x=1756271380; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=CIvKikOPhEGLHf7EWowVUA0K+rreGMGnHAgAKNeRrJk=; b=ftlakTUv6pCgL/5C/7tt5UiSB525t+Zc23bY8Ro1Z0xcGqAWrSfb3+ly 3s7097R/2A1X7DXvhuk0m+RS07kNlBMtV9y5pkROlXvDwK7g1NgQfJHha EW5y69AJM0Hv6VrOz1uXc2PcIZcrXvbLw/C+To9Y1hRRdZaGnZdgoNlLC rU7HzL4w7r684faxwH+a43A9iqV6K7yBrECZzJ9QGzgoosTuf3bfQa5qX 6T/tzgrbl38cYXSFC+DbKdl7fy6+nVwlHogOYv7o3uuN9ZHaQJM8Dp15x rZumqcV2GPP/TxgYI00zY1vuxSb0Xw921RRUJHbY/tVxlzrDi4vdiO9aS w==; X-CSE-ConnectionGUID: jWyjv9BAQiaPFpbmdlDf5g== X-CSE-MsgGUID: 5vCeqWLzTk+18wNsA/jL2w== X-IronPort-AV: E=McAfee;i="6700,10204,11176"; a="13230470" X-IronPort-AV: E=Sophos;i="6.10,179,1719903600"; d="scan'208";a="13230470" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2024 22:09:38 -0700 X-CSE-ConnectionGUID: kZ2OVvyJRUahBDIhj4T2/Q== X-CSE-MsgGUID: nuUhmEumSBK3LD55NUWluw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,179,1719903600"; d="scan'208";a="62703855" Received: from ranerica-svr.sc.intel.com ([172.25.110.23]) by orviesa009.jf.intel.com with ESMTP; 26 Aug 2024 22:09:37 -0700 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 , Nikolay Borisov , Huang Ying , Ricardo Neri , linux-kernel@vger.kernel.org Subject: [PATCH v5 1/4] cacheinfo: Check for null last-level cache info Date: Mon, 26 Aug 2024 22:16:32 -0700 Message-Id: <20240827051635.9114-2-ricardo.neri-calderon@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20240827051635.9114-1-ricardo.neri-calderon@linux.intel.com> References: <20240827051635.9114-1-ricardo.neri-calderon@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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. Reviewed-by: Sudeep Holla Signed-off-by: Ricardo Neri Reviewed-by: Andreas Herrmann Tested-by: Andreas Herrmann --- Cc: Andreas Herrmann Cc: Catalin Marinas Cc: Chen Yu Cc: Huang Ying Cc: Len Brown Cc: Nikolay Borisov 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 # 6.3+ --- Changes since v4: * Combined checks for per_cpu_cacheinfo() and cache_leaves() in a single line. (Sudeep) * Added Reviewed-by tag from Sudeep. Thanks! 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 | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c index 23b8cba4a2a3..77f2e0f91589 100644 --- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -58,7 +58,7 @@ bool last_level_cache_is_valid(unsigned int cpu) { struct cacheinfo *llc; =20 - if (!cache_leaves(cpu)) + if (!cache_leaves(cpu) || !per_cpu_cacheinfo(cpu)) return false; =20 llc =3D per_cpu_cacheinfo_idx(cpu, cache_leaves(cpu) - 1); --=20 2.34.1