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Message-ID: <tip-5d5aa3cfca5cf74cd928daf3674642e6004328d1@git.kernel.org>
Date: Mon, 6 Jul 2015 08:36:43 -0700
From: tip-bot for Alexander Popov <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: dvyukov@...gle.com, alpopov@...ecurity.com, tglx@...utronix.de,
torvalds@...ux-foundation.org, peterz@...radead.org,
glider@...gle.com, mingo@...nel.org, hpa@...or.com, bp@...en8.de,
linux-kernel@...r.kernel.org, adech.fo@...il.com,
a.ryabinin@...sung.com
Subject: [tip:x86/urgent] x86/kasan: Fix KASAN shadow region page tables
Commit-ID: 5d5aa3cfca5cf74cd928daf3674642e6004328d1
Gitweb: http://git.kernel.org/tip/5d5aa3cfca5cf74cd928daf3674642e6004328d1
Author: Alexander Popov <alpopov@...ecurity.com>
AuthorDate: Thu, 2 Jul 2015 12:09:34 +0300
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 6 Jul 2015 14:53:13 +0200
x86/kasan: Fix KASAN shadow region page tables
Currently KASAN shadow region page tables created without
respect of physical offset (phys_base). This causes kernel halt
when phys_base is not zero.
So let's initialize KASAN shadow region page tables in
kasan_early_init() using __pa_nodebug() which considers
phys_base.
This patch also separates x86_64_start_kernel() from KASAN low
level details by moving kasan_map_early_shadow(init_level4_pgt)
into kasan_early_init().
Remove the comment before clear_bss() which stopped bringing
much profit to the code readability. Otherwise describing all
the new order dependencies would be too verbose.
Signed-off-by: Alexander Popov <alpopov@...ecurity.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
Cc: <stable@...r.kernel.org> # 4.0+
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Andrey Konovalov <adech.fo@...il.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1435828178-10975-3-git-send-email-a.ryabinin@samsung.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/include/asm/kasan.h | 8 ++------
arch/x86/kernel/head64.c | 7 ++-----
arch/x86/kernel/head_64.S | 29 -----------------------------
arch/x86/mm/kasan_init_64.c | 36 ++++++++++++++++++++++++++++++++++--
4 files changed, 38 insertions(+), 42 deletions(-)
diff --git a/arch/x86/include/asm/kasan.h b/arch/x86/include/asm/kasan.h
index 8b22422..74a2a8d 100644
--- a/arch/x86/include/asm/kasan.h
+++ b/arch/x86/include/asm/kasan.h
@@ -14,15 +14,11 @@
#ifndef __ASSEMBLY__
-extern pte_t kasan_zero_pte[];
-extern pte_t kasan_zero_pmd[];
-extern pte_t kasan_zero_pud[];
-
#ifdef CONFIG_KASAN
-void __init kasan_map_early_shadow(pgd_t *pgd);
+void __init kasan_early_init(void);
void __init kasan_init(void);
#else
-static inline void kasan_map_early_shadow(pgd_t *pgd) { }
+static inline void kasan_early_init(void) { }
static inline void kasan_init(void) { }
#endif
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 65c8985..f129a9a 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -161,13 +161,12 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
/* Kill off the identity-map trampoline */
reset_early_page_tables();
- kasan_map_early_shadow(early_level4_pgt);
-
- /* clear bss before set_intr_gate with early_idt_handler */
clear_bss();
clear_page(init_level4_pgt);
+ kasan_early_init();
+
for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
set_intr_gate(i, early_idt_handler_array[i]);
load_idt((const struct desc_ptr *)&idt_descr);
@@ -182,8 +181,6 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
/* set init_level4_pgt kernel high mapping*/
init_level4_pgt[511] = early_level4_pgt[511];
- kasan_map_early_shadow(init_level4_pgt);
-
x86_64_start_reservations(real_mode_data);
}
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index e5c27f7..1d40ca8 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -516,38 +516,9 @@ ENTRY(phys_base)
/* This must match the first entry in level2_kernel_pgt */
.quad 0x0000000000000000
-#ifdef CONFIG_KASAN
-#define FILL(VAL, COUNT) \
- .rept (COUNT) ; \
- .quad (VAL) ; \
- .endr
-
-NEXT_PAGE(kasan_zero_pte)
- FILL(kasan_zero_page - __START_KERNEL_map + _KERNPG_TABLE, 512)
-NEXT_PAGE(kasan_zero_pmd)
- FILL(kasan_zero_pte - __START_KERNEL_map + _KERNPG_TABLE, 512)
-NEXT_PAGE(kasan_zero_pud)
- FILL(kasan_zero_pmd - __START_KERNEL_map + _KERNPG_TABLE, 512)
-
-#undef FILL
-#endif
-
-
#include "../../x86/xen/xen-head.S"
__PAGE_ALIGNED_BSS
NEXT_PAGE(empty_zero_page)
.skip PAGE_SIZE
-#ifdef CONFIG_KASAN
-/*
- * This page used as early shadow. We don't use empty_zero_page
- * at early stages, stack instrumentation could write some garbage
- * to this page.
- * Latter we reuse it as zero shadow for large ranges of memory
- * that allowed to access, but not instrumented by kasan
- * (vmalloc/vmemmap ...).
- */
-NEXT_PAGE(kasan_zero_page)
- .skip PAGE_SIZE
-#endif
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 4860906..0e4a05f 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -11,7 +11,19 @@
extern pgd_t early_level4_pgt[PTRS_PER_PGD];
extern struct range pfn_mapped[E820_X_MAX];
-extern unsigned char kasan_zero_page[PAGE_SIZE];
+static pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
+static pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
+static pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
+
+/*
+ * This page used as early shadow. We don't use empty_zero_page
+ * at early stages, stack instrumentation could write some garbage
+ * to this page.
+ * Latter we reuse it as zero shadow for large ranges of memory
+ * that allowed to access, but not instrumented by kasan
+ * (vmalloc/vmemmap ...).
+ */
+static unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
static int __init map_range(struct range *range)
{
@@ -36,7 +48,7 @@ static void __init clear_pgds(unsigned long start,
pgd_clear(pgd_offset_k(start));
}
-void __init kasan_map_early_shadow(pgd_t *pgd)
+static void __init kasan_map_early_shadow(pgd_t *pgd)
{
int i;
unsigned long start = KASAN_SHADOW_START;
@@ -166,6 +178,26 @@ static struct notifier_block kasan_die_notifier = {
};
#endif
+void __init kasan_early_init(void)
+{
+ int i;
+ pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL;
+ pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
+ pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
+
+ for (i = 0; i < PTRS_PER_PTE; i++)
+ kasan_zero_pte[i] = __pte(pte_val);
+
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ kasan_zero_pmd[i] = __pmd(pmd_val);
+
+ for (i = 0; i < PTRS_PER_PUD; i++)
+ kasan_zero_pud[i] = __pud(pud_val);
+
+ kasan_map_early_shadow(early_level4_pgt);
+ kasan_map_early_shadow(init_level4_pgt);
+}
+
void __init kasan_init(void)
{
int i;
--
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