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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D55EC43334 for ; Thu, 23 Jun 2022 18:24:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237218AbiFWSY4 (ORCPT ); Thu, 23 Jun 2022 14:24:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237598AbiFWSXA (ORCPT ); Thu, 23 Jun 2022 14:23:00 -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 17F4569FA4; Thu, 23 Jun 2022 10:25:39 -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 2E40561BFA; Thu, 23 Jun 2022 17:25:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E4C55C3411B; Thu, 23 Jun 2022 17:25:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656005138; bh=/1LJG4oZTcqnV2VpWU4XssJhTWNruaNMjNv7eQ7ewtk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dqyPnI6jiquPq31wdOIaZzjY3cjge2djvxCc2FI48wwBmykoMyFhGuIJJIaHPQDf1 ZtgVIPe3TtXGSmpBo0oTN3uQJxSvulno3EdyoYEAXUro4kJvXp5uIDVgw9VyAp1w4l EwxCACtdKdmPYA6RFh6pWOWsTOqEJO+bMROZ0EG0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kees Cook , Borislav Petkov , Guenter Roeck , Jiri Slaby Subject: [PATCH 5.18 06/11] x86/boot: Wrap literal addresses in absolute_pointer() Date: Thu, 23 Jun 2022 18:45:18 +0200 Message-Id: <20220623164322.500778833@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220623164322.315085512@linuxfoundation.org> References: <20220623164322.315085512@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: Kees Cook commit aeb84412037b89e06f45e382f044da6f200e12f8 upstream. GCC 11 (incorrectly[1]) assumes that literal values cast to (void *) should be treated like a NULL pointer with an offset, and raises diagnostics when doing bounds checking under -Warray-bounds. GCC 12 got "smarter" about finding these: In function 'rdfs8', inlined from 'vga_recalc_vertical' at /srv/code/arch/x86/boot/video-mode.c:124:29, inlined from 'set_mode' at /srv/code/arch/x86/boot/video-mode.c:163:3: /srv/code/arch/x86/boot/boot.h:114:9: warning: array subscript 0 is outside array bounds of 'u8[0]' {aka 'unsigned char[]'} [-Warray-bounds] 114 | asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); | ^~~ This has been solved in other places[2] already by using the recently added absolute_pointer() macro. Do the same here. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 [2] https://lore.kernel.org/all/20210912160149.2227137-1-linux@roeck-us.net/ Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20220227195918.705219-1-keescook@chromium.org Cc: Jiri Slaby Signed-off-by: Greg Kroah-Hartman --- arch/x86/boot/boot.h | 36 ++++++++++++++++++++++++------------ arch/x86/boot/main.c | 2 +- 2 files changed, 25 insertions(+), 13 deletions(-) --- a/arch/x86/boot/boot.h +++ b/arch/x86/boot/boot.h @@ -110,66 +110,78 @@ typedef unsigned int addr_t; static inline u8 rdfs8(addr_t addr) { + u8 *ptr = (u8 *)absolute_pointer(addr); u8 v; - asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); + asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*ptr)); return v; } static inline u16 rdfs16(addr_t addr) { + u16 *ptr = (u16 *)absolute_pointer(addr); u16 v; - asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); + asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline u32 rdfs32(addr_t addr) { + u32 *ptr = (u32 *)absolute_pointer(addr); u32 v; - asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); + asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline void wrfs8(u8 v, addr_t addr) { - asm volatile("movb %1,%%fs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); + u8 *ptr = (u8 *)absolute_pointer(addr); + asm volatile("movb %1,%%fs:%0" : "+m" (*ptr) : "qi" (v)); } static inline void wrfs16(u16 v, addr_t addr) { - asm volatile("movw %1,%%fs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); + u16 *ptr = (u16 *)absolute_pointer(addr); + asm volatile("movw %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); } static inline void wrfs32(u32 v, addr_t addr) { - asm volatile("movl %1,%%fs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); + u32 *ptr = (u32 *)absolute_pointer(addr); + asm volatile("movl %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); } static inline u8 rdgs8(addr_t addr) { + u8 *ptr = (u8 *)absolute_pointer(addr); u8 v; - asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); + asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*ptr)); return v; } static inline u16 rdgs16(addr_t addr) { + u16 *ptr = (u16 *)absolute_pointer(addr); u16 v; - asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); + asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline u32 rdgs32(addr_t addr) { + u32 *ptr = (u32 *)absolute_pointer(addr); u32 v; - asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); + asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline void wrgs8(u8 v, addr_t addr) { - asm volatile("movb %1,%%gs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); + u8 *ptr = (u8 *)absolute_pointer(addr); + asm volatile("movb %1,%%gs:%0" : "+m" (*ptr) : "qi" (v)); } static inline void wrgs16(u16 v, addr_t addr) { - asm volatile("movw %1,%%gs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); + u16 *ptr = (u16 *)absolute_pointer(addr); + asm volatile("movw %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); } static inline void wrgs32(u32 v, addr_t addr) { - asm volatile("movl %1,%%gs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); + u32 *ptr = (u32 *)absolute_pointer(addr); + asm volatile("movl %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); } /* Note: these only return true/false, not a signed return value! */ --- a/arch/x86/boot/main.c +++ b/arch/x86/boot/main.c @@ -33,7 +33,7 @@ static void copy_boot_params(void) u16 cl_offset; }; const struct old_cmdline * const oldcmd = - (const struct old_cmdline *)OLD_CL_ADDRESS; + absolute_pointer(OLD_CL_ADDRESS); BUILD_BUG_ON(sizeof(boot_params) != 4096); memcpy(&boot_params.hdr, &hdr, sizeof(hdr));