39d114ddc6
This patch adds arch specific code for kernel address sanitizer (see Documentation/kasan.txt). 1/8 of kernel addresses reserved for shadow memory. There was no big enough hole for this, so virtual addresses for shadow were stolen from vmalloc area. At early boot stage the whole shadow region populated with just one physical page (kasan_zero_page). Later, this page reused as readonly zero shadow for some memory that KASan currently don't track (vmalloc). After mapping the physical memory, pages for shadow memory are allocated and mapped. Functions like memset/memmove/memcpy do a lot of memory accesses. If bad pointer passed to one of these function it is important to catch this. Compiler's instrumentation cannot do this since these functions are written in assembly. KASan replaces memory functions with manually instrumented variants. Original functions declared as weak symbols so strong definitions in mm/kasan/kasan.c could replace them. Original functions have aliases with '__' prefix in name, so we could call non-instrumented variant if needed. Some files built without kasan instrumentation (e.g. mm/slub.c). Original mem* function replaced (via #define) with prefixed variants to disable memory access checks for such files. Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com> Tested-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
31 lines
934 B
Text
31 lines
934 B
Text
ifdef CONFIG_KASAN
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ifdef CONFIG_KASAN_INLINE
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call_threshold := 10000
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else
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call_threshold := 0
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endif
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KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
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CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address
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CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \
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-fasan-shadow-offset=$(KASAN_SHADOW_OFFSET) \
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--param asan-stack=1 --param asan-globals=1 \
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--param asan-instrumentation-with-call-threshold=$(call_threshold))
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ifeq ($(call cc-option, $(CFLAGS_KASAN_MINIMAL) -Werror),)
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ifneq ($(CONFIG_COMPILE_TEST),y)
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$(warning Cannot use CONFIG_KASAN: \
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-fsanitize=kernel-address is not supported by compiler)
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endif
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else
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ifeq ($(CFLAGS_KASAN),)
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ifneq ($(CONFIG_COMPILE_TEST),y)
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$(warning CONFIG_KASAN: compiler does not support all options.\
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Trying minimal configuration)
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endif
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CFLAGS_KASAN := $(CFLAGS_KASAN_MINIMAL)
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endif
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endif
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endif
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