From d321599cf6b861beefe92327476b617435c7fc4a Mon Sep 17 00:00:00 2001 From: Alexander Potapenko Date: Tue, 6 Feb 2018 15:36:20 -0800 Subject: kasan: add functions for unpoisoning stack variables As a code-size optimization, LLVM builds since r279383 may bulk-manipulate the shadow region when (un)poisoning large memory blocks. This requires new callbacks that simply do an uninstrumented memset(). This fixes linking the Clang-built kernel when using KASAN. [arnd@arndb.de: add declarations for internal functions] Link: http://lkml.kernel.org/r/20180105094112.2690475-1-arnd@arndb.de [fengguang.wu@intel.com: __asan_set_shadow_00 can be static] Link: http://lkml.kernel.org/r/20171223125943.GA74341@lkp-ib03 [ghackmann@google.com: fix memset() parameters, and tweak commit message to describe new callbacks] Link: http://lkml.kernel.org/r/20171204191735.132544-6-paullawrence@google.com Signed-off-by: Alexander Potapenko Signed-off-by: Greg Hackmann Signed-off-by: Paul Lawrence Signed-off-by: Fengguang Wu Signed-off-by: Arnd Bergmann Acked-by: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Masahiro Yamada Cc: Matthias Kaehlcke Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kasan/kasan.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'mm/kasan/kasan.c') diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index d96b36088b2f..8aaee42fcfab 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -770,6 +770,21 @@ void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom) } EXPORT_SYMBOL(__asan_allocas_unpoison); +/* Emitted by the compiler to [un]poison local variables. */ +#define DEFINE_ASAN_SET_SHADOW(byte) \ + void __asan_set_shadow_##byte(const void *addr, size_t size) \ + { \ + __memset((void *)addr, 0x##byte, size); \ + } \ + EXPORT_SYMBOL(__asan_set_shadow_##byte) + +DEFINE_ASAN_SET_SHADOW(00); +DEFINE_ASAN_SET_SHADOW(f1); +DEFINE_ASAN_SET_SHADOW(f2); +DEFINE_ASAN_SET_SHADOW(f3); +DEFINE_ASAN_SET_SHADOW(f5); +DEFINE_ASAN_SET_SHADOW(f8); + #ifdef CONFIG_MEMORY_HOTPLUG static int __meminit kasan_mem_notifier(struct notifier_block *nb, unsigned long action, void *data) -- cgit v1.2.3