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Subject[PATCH v11 14/19] 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>
---
arch/x86/include/asm/page_64_types.h | 12 +++++++++---
arch/x86/kernel/Makefile | 2 ++
arch/x86/mm/kasan_init_64.c | 11 +++++++++--
include/linux/init_task.h | 8 ++++++++
mm/kasan/kasan.h | 9 +++++++++
mm/kasan/report.c | 6 ++++++
scripts/Makefile.kasan | 1 +
7 files changed, 44 insertions(+), 5 deletions(-)

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 4fc8ca7..057f6f6 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 3e4d9a1..5350870 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -189,11 +189,18 @@ void __init kasan_init(void)
if (map_range(&pfn_mapped[i]))
panic("kasan: unable to allocate shadow!");
}
-
populate_zero_shadow(kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
- (void *)KASAN_SHADOW_END);
+ kasan_mem_to_shadow((void *)__START_KERNEL_map));
+
+ vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
+ (unsigned long)kasan_mem_to_shadow(_end),
+ NUMA_NO_NODE);
+
+ populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_VADDR),
+ (void *)KASAN_SHADOW_END);

memset(kasan_zero_page, 0, 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 d3d43ec..696d223 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)
@@ -250,6 +257,7 @@ extern struct task_group root_task_group;
INIT_RT_MUTEXES(tsk) \
INIT_VTIME(tsk) \
INIT_NUMA_BALANCING(tsk) \
+ INIT_KASAN(tsk) \
}


diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 5b052ab..1fcc1d8 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -12,6 +12,15 @@
#define KASAN_KMALLOC_REDZONE 0xFC /* redzone inside slub object */
#define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */

+/*
+ * 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
+

struct kasan_access_info {
const void *access_addr;
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 2760edb..866732e 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -64,6 +64,12 @@ static void print_error_description(struct kasan_access_info *info)
case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
bug_type = "out of bounds 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: KASan: %s in %pS at addr %p\n",
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 159396a..0ac7d1d 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -9,6 +9,7 @@ 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),)
--
2.2.2


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