Messages in this thread | | | Subject | Re: [PATCH 2/4] kasan: added functions for unpoisoning stack variables | From | Andrey Ryabinin <> | Date | Mon, 10 Jul 2017 13:31:05 +0300 |
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On 07/07/2017 01:01 AM, Greg Hackmann wrote: > From: Alexander Potapenko <glider@google.com> > > 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. > > Signed-off-by: Alexander Potapenko <glider@google.com> > [ghackmann@google.com: fix memset() parameters, and tweak > commit message to describe new callbacks] > Signed-off-by: Greg Hackmann <ghackmann@google.com> > --- > mm/kasan/kasan.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c > index 892b626f564b..89911e5c69f9 100644 > --- a/mm/kasan/kasan.c > +++ b/mm/kasan/kasan.c > @@ -828,6 +828,21 @@ 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);
I think we can remove f8 as it should be used only by use-after-return instrumentation. We don't use it in the kernel
> + > #ifdef CONFIG_MEMORY_HOTPLUG > static int kasan_mem_notifier(struct notifier_block *nb, > unsigned long action, void *data) >
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