From patchwork Tue Sep 6 00:02:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 12966641 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 13A6EECAAA1 for ; Tue, 6 Sep 2022 00:02:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231965AbiIFACd (ORCPT ); Mon, 5 Sep 2022 20:02:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230315AbiIFACc (ORCPT ); Mon, 5 Sep 2022 20:02:32 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF3FC67455; Mon, 5 Sep 2022 17:02:31 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 80C61611A0; Tue, 6 Sep 2022 00:02:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90616C433D6; Tue, 6 Sep 2022 00:02:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662422550; bh=TMJ80vYAbA8KREyvuRGxIHEH4TEzdMwKMX5gDaCaSJc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kgHE5mLNRCWUku1TGU9On94pxkwpyY6dwuE30/v/4i1/aw9p6AfBvpP/57H+OGHYB o6bCbE1EfvzMx9gUg3k4tzgBYmQ8dHe9IPN5s0424EjjzRggRi+94/K360gzozThZt Nytgw4B8lmopSZxty0i2xuFnZeP3hXVwbbtR3slfFRJogtOZlmd5aTUZ4TS7G8977V VMv3P2oGArApQ4JbY+pcmIzimq0wmQno1NJG/s1bHa+QU6rBKRIMt2NmN7UwYqcfR/ wzhruhloRBnzTzAohr7kw9fZxgOL7LaKi5PdQBjqxtx4wu/xy2cBn2kPGrxPYz0kZj uiwdN0ttTPq8Q== From: Jarkko Sakkinen To: linux-sgx@vger.kernel.org Cc: Haitao Huang , Vijay Dhanraj , Reinette Chatre , Dave Hansen , Kai Huang , Jarkko Sakkinen , stable@vger.kernel.org, Paul Menzel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), "H. Peter Anvin" , linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)) Subject: [PATCH v3 1/2] x86/sgx: Do not fail on incomplete sanitization on premature stop of ksgxd Date: Tue, 6 Sep 2022 03:02:20 +0300 Message-Id: <20220906000221.34286-2-jarkko@kernel.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220906000221.34286-1-jarkko@kernel.org> References: <20220906000221.34286-1-jarkko@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org Unsanitized pages trigger WARN_ON() unconditionally, which can panic the whole computer, if /proc/sys/kernel/panic_on_warn is set. In sgx_init(), if misc_register() fails or misc_register() succeeds but neither sgx_drv_init() nor sgx_vepc_init() succeeds, then ksgxd will be prematurely stopped. This may leave unsanitized pages, which will result a false warning. Refine __sgx_sanitize_pages() to return: 1. Zero when the sanitization process is complete or ksgxd has been requested to stop. 2. The number of unsanitized pages otherwise. Link: https://lore.kernel.org/linux-sgx/20220825051827.246698-1-jarkko@kernel.org/T/#u Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list") Cc: stable@vger.kernel.org # v5.13+ Reported-by: Paul Menzel Signed-off-by: Jarkko Sakkinen Acked-by: Kai Huang Reviewed-by: Reinette Chatre --- v9: - Remove left_dirty declaratio from ksgxd(). - Update commit message. v8: - Discard changes that are not relevant for the stable fix. This does absolutely minimum to address the bug: https://lore.kernel.org/linux-sgx/a5fa56bdc57d6472a306bd8d795afc674b724538.camel@intel.com/ v7: - Rewrote commit message. - Do not return -ECANCELED on premature stop. Instead use zero both premature stop and complete sanitization. v6: - Address Reinette's feedback: https://lore.kernel.org/linux-sgx/Yw6%2FiTzSdSw%2FY%2FVO@kernel.org/ v5: - Add the klog dump and sysctl option to the commit message. v4: - Explain expectations for dirty_page_list in the function header, instead of an inline comment. - Improve commit message to explain the conditions better. - Return the number of pages left dirty to ksgxd() and print warning after the 2nd call, if there are any. v3: - Remove WARN_ON(). - Tuned comments and the commit message a bit. v2: - Replaced WARN_ON() with optional pr_info() inside __sgx_sanitize_pages(). - Rewrote the commit message. - Added the fixes tag. --- arch/x86/kernel/cpu/sgx/main.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 515e2a5f25bb..0aad028f04d4 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -49,9 +49,13 @@ static LIST_HEAD(sgx_dirty_page_list); * Reset post-kexec EPC pages to the uninitialized state. The pages are removed * from the input list, and made available for the page allocator. SECS pages * prepending their children in the input list are left intact. + * + * Return 0 when sanitization was successful or kthread was stopped, and the + * number of unsanitized pages otherwise. */ -static void __sgx_sanitize_pages(struct list_head *dirty_page_list) +static unsigned long __sgx_sanitize_pages(struct list_head *dirty_page_list) { + unsigned long left_dirty = 0; struct sgx_epc_page *page; LIST_HEAD(dirty); int ret; @@ -59,7 +63,7 @@ static void __sgx_sanitize_pages(struct list_head *dirty_page_list) /* dirty_page_list is thread-local, no need for a lock: */ while (!list_empty(dirty_page_list)) { if (kthread_should_stop()) - return; + return 0; page = list_first_entry(dirty_page_list, struct sgx_epc_page, list); @@ -92,12 +96,14 @@ static void __sgx_sanitize_pages(struct list_head *dirty_page_list) } else { /* The page is not yet clean - move to the dirty list. */ list_move_tail(&page->list, &dirty); + left_dirty++; } cond_resched(); } list_splice(&dirty, dirty_page_list); + return left_dirty; } static bool sgx_reclaimer_age(struct sgx_epc_page *epc_page) @@ -395,10 +401,7 @@ static int ksgxd(void *p) * required for SECS pages, whose child pages blocked EREMOVE. */ __sgx_sanitize_pages(&sgx_dirty_page_list); - __sgx_sanitize_pages(&sgx_dirty_page_list); - - /* sanity check: */ - WARN_ON(!list_empty(&sgx_dirty_page_list)); + WARN_ON(__sgx_sanitize_pages(&sgx_dirty_page_list)); while (!kthread_should_stop()) { if (try_to_freeze())