From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85F06C433E0 for ; Fri, 19 Mar 2021 04:07:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52EDD64E61 for ; Fri, 19 Mar 2021 04:07:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233641AbhCSEHB (ORCPT ); Fri, 19 Mar 2021 00:07:01 -0400 Received: from mga11.intel.com ([192.55.52.93]:60155 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233640AbhCSEGc (ORCPT ); Fri, 19 Mar 2021 00:06:32 -0400 IronPort-SDR: Tets64KEt0y6m+PyjoWctdcp4+m4QcTe3nXx7q80+vFHfK7KXHnYtXi+tfuh79/SzGeURJDur+ 8S/kKWntT/gw== X-IronPort-AV: E=McAfee;i="6000,8403,9927"; a="186471728" X-IronPort-AV: E=Sophos;i="5.81,259,1610438400"; d="scan'208";a="186471728" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Mar 2021 21:06:31 -0700 IronPort-SDR: kbyxE+5AtLjLyENpcbJzxr0GaaK7xtFZSCp0v84pClHqUm20XPQzlBZxAol9cSKoMoPuDVmtCd YYRP7gAdE+uQ== X-IronPort-AV: E=Sophos;i="5.81,259,1610438400"; d="scan'208";a="406620937" Received: from dharorix-mobl2.amr.corp.intel.com (HELO khuang2-desk.gar.corp.intel.com) ([10.252.142.226]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Mar 2021 21:06:29 -0700 From: Kai Huang To: x86@kernel.org, linux-sgx@vger.kernel.org Cc: bp@alien8.de, jarkko@kernel.org, dave.hansen@linux.intel.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, Kai Huang Subject: [PATCH] x86/sgx: Avoid returning NULL in __sgx_alloc_epc_page() Date: Fri, 19 Mar 2021 17:06:02 +1300 Message-Id: <20210319040602.178558-1-kai.huang@intel.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Below kernel bug happened when running simple SGX application when EPC is under pressure. The root cause is with commit 5b8719504e3a ("x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()"), __sgx_alloc_epc_page() returns NULL when there's no free EPC page can be allocated, while old behavior was it always returned ERR_PTR(-ENOMEM) in such case. Fix by directly returning the page if __sgx_alloc_epc_page_from_node() allocates a valid page in fallback to non-local allocation, and always returning ERR_PTR(-ENOMEM) if no EPC page can be allocated. [ 253.474764] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 253.500101] #PF: supervisor write access in kernel mode [ 253.525462] #PF: error_code(0x0002) - not-present page ... [ 254.102041] Call Trace: [ 254.126699] sgx_ioc_enclave_add_pages+0x241/0x770 [ 254.151305] sgx_ioctl+0x194/0x4b0 [ 254.174976] ? handle_mm_fault+0xd0/0x260 [ 254.198470] ? do_user_addr_fault+0x1ef/0x570 [ 254.221827] __x64_sys_ioctl+0x91/0xc0 [ 254.244546] do_syscall_64+0x38/0x90 [ 254.266728] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 254.289232] RIP: 0033:0x7fdc4cf4031b ... [ 254.711480] CR2: 0000000000000008 [ 254.735494] ---[ end trace 970dce6d4cdf7f64 ]--- [ 254.759915] RIP: 0010:sgx_alloc_epc_page+0x46/0x152 ... Fixes: 5b8719504e3a("x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()") Signed-off-by: Kai Huang --- arch/x86/kernel/cpu/sgx/main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index fe26e7e91c25..7105e34da530 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -508,10 +508,10 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void) page = __sgx_alloc_epc_page_from_node(nid); if (page) - break; + return page; } - return page; + return ERR_PTR(-ENOMEM); } /** -- 2.30.2