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=-19.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 1FB43C41537 for ; Mon, 26 Jul 2021 16:36:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 10F5360F5E for ; Mon, 26 Jul 2021 16:36:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240348AbhGZPzV (ORCPT ); Mon, 26 Jul 2021 11:55:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:51906 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237855AbhGZPeu (ORCPT ); Mon, 26 Jul 2021 11:34:50 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 858706056B; Mon, 26 Jul 2021 16:15:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627316118; bh=ZzRv0JOfJjaUGMuerpvp3Et3Y0kb7NsmdPJtLOwTmOU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nHK7UbVrDyIAndmMm15I3nx4Qzptt45Ze5pb9p6HMdxrQj4ZwUsQTXttuEbMsAN0b 1IVOU9Koq2+2edYNFrJCIGWFDzukdE+mrYWZCrkS9Ban74hEGeJ4AA4AdMdbkXydVP Jn9Xg5uoAjxmq3f0GKC7CHYUt5klXYNaDfEtJcXI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , Linus Torvalds Subject: [PATCH 5.13 196/223] kfence: move the size check to the beginning of __kfence_alloc() Date: Mon, 26 Jul 2021 17:39:48 +0200 Message-Id: <20210726153852.606420670@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210726153846.245305071@linuxfoundation.org> References: <20210726153846.245305071@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexander Potapenko commit 235a85cb32bb123854ad31de46fdbf04c1d57cda upstream. Check the allocation size before toggling kfence_allocation_gate. This way allocations that can't be served by KFENCE will not result in waiting for another CONFIG_KFENCE_SAMPLE_INTERVAL without allocating anything. Link: https://lkml.kernel.org/r/20210714092222.1890268-1-glider@google.com Signed-off-by: Alexander Potapenko Suggested-by: Marco Elver Reviewed-by: Marco Elver Cc: Dmitry Vyukov Cc: Marco Elver Cc: Greg Kroah-Hartman Cc: [5.12+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/kfence/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -734,6 +734,13 @@ void kfence_shutdown_cache(struct kmem_c void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) { /* + * Perform size check before switching kfence_allocation_gate, so that + * we don't disable KFENCE without making an allocation. + */ + if (size > PAGE_SIZE) + return NULL; + + /* * allocation_gate only needs to become non-zero, so it doesn't make * sense to continue writing to it and pay the associated contention * cost, in case we have a large number of concurrent allocations. @@ -757,9 +764,6 @@ void *__kfence_alloc(struct kmem_cache * if (!READ_ONCE(kfence_enabled)) return NULL; - if (size > PAGE_SIZE) - return NULL; - return kfence_guarded_alloc(s, size, flags); }