linux-kernel - [PATCH v3 05/19] x86/kasan/64: Teach KASAN about the cpu_entry

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Date:   Thu, 23 Nov 2017 20:32:51 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     X86 ML <x86@...nel.org>
Cc:     Borislav Petkov <bpetkov@...e.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Brian Gerst <brgerst@...il.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com
Subject: [PATCH v3 05/19] x86/kasan/64: Teach KASAN about the cpu_entry_area

The cpu_entry_area will contain stacks.  Make sure that KASAN has
appropriate shadow mappings for them.

Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: kasan-dev@...glegroups.com
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/mm/kasan_init_64.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 99dfed6dfef8..54561dce742e 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -277,6 +277,7 @@ void __init kasan_early_init(void)
 void __init kasan_init(void)
 {
 	int i;
+	void *cpu_entry_area_begin, *cpu_entry_area_end;
 
 #ifdef CONFIG_KASAN_INLINE
 	register_die_notifier(&kasan_die_notifier);
@@ -329,8 +330,18 @@ void __init kasan_init(void)
 			      (unsigned long)kasan_mem_to_shadow(_end),
 			      early_pfn_to_nid(__pa(_stext)));
 
+	cpu_entry_area_begin = (void *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_BOTTOM));
+	cpu_entry_area_end = (void *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_TOP) + PAGE_SIZE);
+
 	kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
-			(void *)KASAN_SHADOW_END);
+				   kasan_mem_to_shadow(cpu_entry_area_begin));
+
+	kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(cpu_entry_area_begin),
+			      (unsigned long)kasan_mem_to_shadow(cpu_entry_area_end),
+		0);
+
+	kasan_populate_zero_shadow(kasan_mem_to_shadow(cpu_entry_area_end),
+				   (void *)KASAN_SHADOW_END);
 
 	load_cr3(init_top_pgt);
 	__flush_tlb_all();
-- 
2.13.6