Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932213AbdCWD2K (ORCPT ); Wed, 22 Mar 2017 23:28:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36538 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932128AbdCWD1n (ORCPT ); Wed, 22 Mar 2017 23:27:43 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 5D05A61D16 Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=bhe@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 5D05A61D16 From: Baoquan He To: linux-kernel@vger.kernel.org Cc: Baoquan He , , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Thomas Garnier , Kees Cook , Borislav Petkov , Andrew Morton , Masahiro Yamada Subject: [PATCH v1 RESEND 1/2] x86/mm/KASLR: EFI region is mistakenly included into KASLR VA space for randomization Date: Thu, 23 Mar 2017 11:27:34 +0800 Message-Id: <1490239655-20902-2-git-send-email-bhe@redhat.com> In-Reply-To: <1490239655-20902-1-git-send-email-bhe@redhat.com> References: <1490239655-20902-1-git-send-email-bhe@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 23 Mar 2017 03:27:43 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2379 Lines: 59 Currently KASLR is enabled on three regions: the direct mapping of physical memory, vamlloc and vmemmap. However EFI region is also mistakenly included for VA space randomization because of misusing EFI_VA_START macro and assuming EFI_VA_START < EFI_VA_END. The EFI region is reserved for EFI runtime services virtual mapping which should not be included in kaslr ranges. It will be re-used by kexec/kdump kernel, the mistake may cause failure when jump to kexec/kdump kernel if vmemmap allocation stomps on the allocated efi mapping region. In Documentation/x86/x86_64/mm.txt, we can see: ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space EFI use the space from -4G to -64G thus EFI_VA_START > EFI_VA_END Here EFI_VA_START = -4G, and EFI_VA_END = -64G Changing EFI_VA_START to EFI_VA_END in mm/kaslr.c fixes this problem. Cc: #4.8+ Signed-off-by: Baoquan He Acked-by: Dave Young Reviewed-by: Bhupesh Sharma Acked-by: Thomas Garnier Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: Thomas Garnier Cc: Kees Cook Cc: Borislav Petkov Cc: Andrew Morton Cc: Masahiro Yamada --- arch/x86/mm/kaslr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c index 887e571..aed2064 100644 --- a/arch/x86/mm/kaslr.c +++ b/arch/x86/mm/kaslr.c @@ -48,7 +48,7 @@ static const unsigned long vaddr_start = __PAGE_OFFSET_BASE; #if defined(CONFIG_X86_ESPFIX64) static const unsigned long vaddr_end = ESPFIX_BASE_ADDR; #elif defined(CONFIG_EFI) -static const unsigned long vaddr_end = EFI_VA_START; +static const unsigned long vaddr_end = EFI_VA_END; #else static const unsigned long vaddr_end = __START_KERNEL_map; #endif @@ -105,7 +105,7 @@ void __init kernel_randomize_memory(void) */ BUILD_BUG_ON(vaddr_start >= vaddr_end); BUILD_BUG_ON(IS_ENABLED(CONFIG_X86_ESPFIX64) && - vaddr_end >= EFI_VA_START); + vaddr_end >= EFI_VA_END); BUILD_BUG_ON((IS_ENABLED(CONFIG_X86_ESPFIX64) || IS_ENABLED(CONFIG_EFI)) && vaddr_end >= __START_KERNEL_map); -- 2.5.5