From patchwork Wed Jan 22 17:52:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11346207 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C475617EA for ; Wed, 22 Jan 2020 17:52:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3A3224656 for ; Wed, 22 Jan 2020 17:52:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="najcw7ip" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729030AbgAVRwy (ORCPT ); Wed, 22 Jan 2020 12:52:54 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:5565 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728827AbgAVRwx (ORCPT ); Wed, 22 Jan 2020 12:52:53 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 482tKY450Pz9vBf4; Wed, 22 Jan 2020 18:52:49 +0100 (CET) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=najcw7ip; dkim-adsp=pass; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id 2vbxDVXx3gT8; Wed, 22 Jan 2020 18:52:49 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 482tKY348bz9vBf1; Wed, 22 Jan 2020 18:52:49 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1579715569; bh=Wl+zaBbMBZgvhufq6pfrc9DXJ49WhaqTuzhVpUiFLfc=; h=In-Reply-To:References:From:Subject:To:Cc:Date:From; b=najcw7ipVpyl+ds1ybPWEWZx+Trqykq2FxH5AIjJ30tw07JF6/cNp4jIt8m0CpJeD wP4sRYVC6CHoqC1gOZDF9buVV+XHf19z0DrlNATjwVUMcvrK+DW5G3ESN4BzvfF9kH YZdGZ/BD0xWu+IDv5XGoNUvkiz+i+CEVEtflYF7s= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 251308B810; Wed, 22 Jan 2020 18:52:51 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id lXx_an0ltPsO; Wed, 22 Jan 2020 18:52:51 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id DAC3D8B7FE; Wed, 22 Jan 2020 18:52:50 +0100 (CET) Received: by localhost.localdomain (Postfix, from userid 0) id B3ABD651E0; Wed, 22 Jan 2020 17:52:50 +0000 (UTC) Message-Id: In-Reply-To: <12a4be679e43de1eca6e5e2173163f27e2f25236.1579715466.git.christophe.leroy@c-s.fr> References: <12a4be679e43de1eca6e5e2173163f27e2f25236.1579715466.git.christophe.leroy@c-s.fr> From: Christophe Leroy Subject: [PATCH v2 4/6] powerpc/32s: Drop NULL addr verification To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Wed, 22 Jan 2020 17:52:50 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org NULL addr is a user address. Don't waste time checking it. If someone tries to access it, it will SIGFAULT the same way as for address 1, so no need to make it special. The special case is when not doing a write, in that case we want to drop the entire function. This is now handled by 'dir' param and not by the nulity of 'to' anymore. Also make beginning of prevent_user_access() similar to beginning of allow_user_access(), and tell the compiler that writing in kernel space or with a 0 length is unlikely Signed-off-by: Christophe Leroy --- v2: no change --- arch/powerpc/include/asm/book3s/32/kup.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index d765515bd1c1..3c1798e56b55 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -113,7 +113,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user addr = (__force u32)to; - if (!addr || addr >= TASK_SIZE || !size) + if (unlikely(addr >= TASK_SIZE || !size)) return; end = min(addr + size, TASK_SIZE); @@ -124,16 +124,18 @@ static __always_inline void allow_user_access(void __user *to, const void __user static __always_inline void prevent_user_access(void __user *to, const void __user *from, u32 size, unsigned long dir) { - u32 addr = (__force u32)to; - u32 end = min(addr + size, TASK_SIZE); + u32 addr, end; BUILD_BUG_ON(!__builtin_constant_p(dir)); if (!(dir & KUAP_W)) return; - if (!addr || addr >= TASK_SIZE || !size) + addr = (__force u32)to; + + if (unlikely(addr >= TASK_SIZE || !size)) return; + end = min(addr + size, TASK_SIZE); current->thread.kuap = 0; kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */ }