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Subject[PATCH v9 12/17] kasan: enable stack instrumentation
Date
Stack instrumentation allows to detect out of bounds
memory accesses for variables allocated on stack.
Compiler adds redzones around every variable on stack
and poisons redzones in function's prologue.

Such approach significantly increases stack usage,
so all in-kernel stacks size were doubled.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
---
Makefile | 1 +
arch/x86/include/asm/page_64_types.h | 12 +++++++++---
arch/x86/kernel/Makefile | 2 ++
arch/x86/mm/kasan_init_64.c | 8 ++++++++
include/linux/init_task.h | 8 ++++++++
include/linux/kasan.h | 9 +++++++++
mm/kasan/report.c | 6 ++++++
7 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index ee5830b..02530fa 100644
--- a/Makefile
+++ b/Makefile
@@ -755,6 +755,7 @@ CFLAGS_KASAN_MINIMAL := $(call cc-option, -fsanitize=kernel-address)

CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \
-fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \
+ --param asan-stack=1 \
--param asan-instrumentation-with-call-threshold=$(call_threshold))

ifeq ($(CFLAGS_KASAN_MINIMAL),)
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 75450b2..4edd53b 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -1,17 +1,23 @@
#ifndef _ASM_X86_PAGE_64_DEFS_H
#define _ASM_X86_PAGE_64_DEFS_H

-#define THREAD_SIZE_ORDER 2
+#ifdef CONFIG_KASAN
+#define KASAN_STACK_ORDER 1
+#else
+#define KASAN_STACK_ORDER 0
+#endif
+
+#define THREAD_SIZE_ORDER (2 + KASAN_STACK_ORDER)
#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
#define CURRENT_MASK (~(THREAD_SIZE - 1))

-#define EXCEPTION_STACK_ORDER 0
+#define EXCEPTION_STACK_ORDER (0 + KASAN_STACK_ORDER)
#define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)

#define DEBUG_STACK_ORDER (EXCEPTION_STACK_ORDER + 1)
#define DEBUG_STKSZ (PAGE_SIZE << DEBUG_STACK_ORDER)

-#define IRQ_STACK_ORDER 2
+#define IRQ_STACK_ORDER (2 + KASAN_STACK_ORDER)
#define IRQ_STACK_SIZE (PAGE_SIZE << IRQ_STACK_ORDER)

#define DOUBLEFAULT_STACK 1
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 74d3f3e..fae4c4e 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -17,6 +17,8 @@ CFLAGS_REMOVE_early_printk.o = -pg
endif

KASAN_SANITIZE_head$(BITS).o := n
+KASAN_SANITIZE_dumpstack.o := n
+KASAN_SANITIZE_dumpstack_$(BITS).o := n

CFLAGS_irq.o := -I$(src)/../include/asm/trace

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 70e8082..042f404 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -207,9 +207,17 @@ void __init kasan_init(void)
kasan_mem_to_shadow(KASAN_SHADOW_END));

populate_zero_shadow(kasan_mem_to_shadow(KASAN_SHADOW_END),
+ kasan_mem_to_shadow(__START_KERNEL_map));
+
+ vmemmap_populate(kasan_mem_to_shadow((unsigned long)_stext),
+ kasan_mem_to_shadow((unsigned long)_end),
+ NUMA_NO_NODE);
+
+ populate_zero_shadow(kasan_mem_to_shadow(MODULES_VADDR),
KASAN_SHADOW_END);

memset(kasan_poisoned_page, KASAN_SHADOW_GAP, PAGE_SIZE);

load_cr3(init_level4_pgt);
+ init_task.kasan_depth = 0;
}
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 3037fc0..3932e0a 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -175,6 +175,13 @@ extern struct task_group root_task_group;
# define INIT_NUMA_BALANCING(tsk)
#endif

+#ifdef CONFIG_KASAN
+# define INIT_KASAN(tsk) \
+ .kasan_depth = 1,
+#else
+# define INIT_KASAN(tsk)
+#endif
+
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -247,6 +254,7 @@ extern struct task_group root_task_group;
INIT_RT_MUTEXES(tsk) \
INIT_VTIME(tsk) \
INIT_NUMA_BALANCING(tsk) \
+ INIT_KASAN(tsk) \
}


diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 940fc4f..f8eca6a 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -17,6 +17,15 @@ struct page;
#define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */
#define KASAN_SHADOW_GAP 0xF9 /* address belongs to shadow memory */

+/*
+ * Stack redzone shadow values
+ * (Those are compiler's ABI, don't change them)
+ */
+#define KASAN_STACK_LEFT 0xF1
+#define KASAN_STACK_MID 0xF2
+#define KASAN_STACK_RIGHT 0xF3
+#define KASAN_STACK_PARTIAL 0xF4
+
#include <asm/kasan.h>
#include <linux/sched.h>

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index f9bc57a..faa07f0 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -67,6 +67,12 @@ static void print_error_description(struct access_info *info)
case KASAN_SHADOW_GAP:
bug_type = "wild memory access";
break;
+ case KASAN_STACK_LEFT:
+ case KASAN_STACK_MID:
+ case KASAN_STACK_RIGHT:
+ case KASAN_STACK_PARTIAL:
+ bug_type = "out of bounds on stack";
+ break;
}

pr_err("BUG: AddressSanitizer: %s in %pS at addr %p\n",
--
2.2.1


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