linux-kernel - [PATCH 2/2] x86/mm/KASLR: Correct the upper boundary of KALSR mm regions if adjacent to EFI

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Date:   Wed,  8 Mar 2017 15:47:38 +0800
From:   Baoquan He <bhe@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-efi@...r.kernel.org, thgarnie@...gle.com,
        keescook@...omium.org, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, akpm@...ux-foundation.org,
        dyoung@...hat.com, Baoquan He <bhe@...hat.com>
Subject: [PATCH 2/2] x86/mm/KASLR: Correct the upper boundary of KALSR mm regions if adjacent to EFI

EFI allocates runtime services regions top-down, starting from EFI_VA_START
to EFI_VA_END. So EFI_VA_START is bigger than EFI_VA_END and is the end of
EFI region. The upper boundary of memory regions randomized by KASLR should
be EFI_VA_END if it's adjacent to EFI region, but not EFI_VA_START.

Correct it in this patch.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 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