From d5d44e7e3507b0ad868f68e0c5bca6a57afa1b8b Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sun, 25 Oct 2020 23:50:09 +0100 Subject: ARM: 9013/2: Disable KASan instrumentation for some code Disable instrumentation for arch/arm/boot/compressed/* since that code is executed before the kernel has even set up its mappings and definately out of scope for KASan. Disable instrumentation of arch/arm/vdso/* because that code is not linked with the kernel image, so the KASan management code would fail to link. Disable instrumentation of arch/arm/mm/physaddr.c. See commit ec6d06efb0ba ("arm64: Add support for CONFIG_DEBUG_VIRTUAL") for more details. Disable kasan check in the function unwind_pop_register because it does not matter that kasan checks failed when unwind_pop_register() reads the stack memory of a task. Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Reviewed-by: Ard Biesheuvel Tested-by: Ard Biesheuvel # QEMU/KVM/mach-virt/LPAE/8G Tested-by: Florian Fainelli # Brahma SoCs Tested-by: Ahmad Fatoum # i.MX6Q Reported-by: Florian Fainelli Reported-by: Marc Zyngier Signed-off-by: Abbott Liu Signed-off-by: Florian Fainelli Signed-off-by: Linus Walleij Signed-off-by: Russell King --- arch/arm/boot/compressed/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm/boot') diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index 47f001ca5499..a815b1ae990d 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -24,6 +24,7 @@ OBJS += hyp-stub.o endif GCOV_PROFILE := n +KASAN_SANITIZE := n # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. KCOV_INSTRUMENT := n -- cgit From d6d51a96c7d63b7450860a3037f2d62388286a52 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sun, 25 Oct 2020 23:52:08 +0100 Subject: ARM: 9014/2: Replace string mem* functions for KASan Functions like memset()/memmove()/memcpy() do a lot of memory accesses. If a bad pointer is passed to one of these functions it is important to catch this. Compiler instrumentation cannot do this since these functions are written in assembly. KASan replaces these memory functions with instrumented variants. The original functions are declared as weak symbols so that the strong definitions in mm/kasan/kasan.c can replace them. The original functions have aliases with a '__' prefix in their name, so we can call the non-instrumented variant if needed. We must use __memcpy()/__memset() in place of memcpy()/memset() when we copy .data to RAM and when we clear .bss, because kasan_early_init cannot be called before the initialization of .data and .bss. For the kernel compression and EFI libstub's custom string libraries we need a special quirk: even if these are built without KASan enabled, they rely on the global headers for their custom string libraries, which means that e.g. memcpy() will be defined to __memcpy() and we get link failures. Since these implementations are written i C rather than assembly we use e.g. __alias(memcpy) to redirected any users back to the local implementation. Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Reviewed-by: Ard Biesheuvel Tested-by: Ard Biesheuvel # QEMU/KVM/mach-virt/LPAE/8G Tested-by: Florian Fainelli # Brahma SoCs Tested-by: Ahmad Fatoum # i.MX6Q Reported-by: Russell King - ARM Linux Signed-off-by: Ahmad Fatoum Signed-off-by: Abbott Liu Signed-off-by: Florian Fainelli Signed-off-by: Linus Walleij Signed-off-by: Russell King --- arch/arm/boot/compressed/string.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'arch/arm/boot') diff --git a/arch/arm/boot/compressed/string.c b/arch/arm/boot/compressed/string.c index ade5079bebbf..8c0fa276d994 100644 --- a/arch/arm/boot/compressed/string.c +++ b/arch/arm/boot/compressed/string.c @@ -7,6 +7,25 @@ #include +/* + * The decompressor is built without KASan but uses the same redirects as the + * rest of the kernel when CONFIG_KASAN is enabled, defining e.g. memcpy() + * to __memcpy() but since we are not linking with the main kernel string + * library in the decompressor, that will lead to link failures. + * + * Undefine KASan's versions, define the wrapped functions and alias them to + * the right names so that when e.g. __memcpy() appear in the code, it will + * still be linked to this local version of memcpy(). + */ +#ifdef CONFIG_KASAN +#undef memcpy +#undef memmove +#undef memset +void *__memcpy(void *__dest, __const void *__src, size_t __n) __alias(memcpy); +void *__memmove(void *__dest, __const void *__src, size_t count) __alias(memmove); +void *__memset(void *s, int c, size_t count) __alias(memset); +#endif + void *memcpy(void *__dest, __const void *__src, size_t __n) { int i = 0; -- cgit