From mboxrd@z Thu Jan 1 00:00:00 1970 From: Baoquan He Subject: [PATCH v2] x86/mm/KASLR: EFI region is mistakenly included into KASLR VA space for randomization Date: Fri, 24 Mar 2017 12:59:52 +0800 Message-ID: <1490331592-31860-1-git-send-email-bhe@redhat.com> Return-path: Sender: stable-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Baoquan He , stable@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-efi@vger.kernel.org, Thomas Garnier , Kees Cook , Borislav Petkov , Andrew Morton , Masahiro Yamada , Dave Young , Bhupesh Sharma List-Id: linux-efi@vger.kernel.org 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. 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: linux-efi@vger.kernel.org Cc: Thomas Garnier Cc: Kees Cook Cc: Borislav Petkov Cc: Andrew Morton Cc: Masahiro Yamada Cc: Dave Young Cc: Bhupesh Sharma --- v1->v2: No code change, just update patch log according to reviewer's comment. 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