Messages in this thread | | | Subject | Re: [PATCH v2 06/18] x86/kasan/64: Teach KASAN about the cpu_entry_area | From | Andrey Ryabinin <> | Date | Thu, 23 Nov 2017 13:08:41 +0300 |
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On 11/22/2017 06:22 PM, Andy Lutomirski wrote: > On Wed, Nov 22, 2017 at 1:05 AM, Andrey Ryabinin > <aryabinin@virtuozzo.com> wrote: >> >> >> On 11/22/2017 07:44 AM, Andy Lutomirski wrote: >>> The cpu_entry_area will contain stacks. Make sure that KASAN has >>> appropriate shadow mappings for them. >>> >>> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> >>> Cc: Alexander Potapenko <glider@google.com> >>> Cc: Dmitry Vyukov <dvyukov@google.com> >>> Cc: kasan-dev@googlegroups.com >>> Signed-off-by: Andy Lutomirski <luto@kernel.org> >>> --- >>> arch/x86/mm/kasan_init_64.c | 9 ++++++++- >>> 1 file changed, 8 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c >>> index 99dfed6dfef8..43d376687315 100644 >>> --- a/arch/x86/mm/kasan_init_64.c >>> +++ b/arch/x86/mm/kasan_init_64.c >>> @@ -330,7 +330,14 @@ void __init kasan_init(void) >>> early_pfn_to_nid(__pa(_stext))); >>> >>> kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END), >>> - (void *)KASAN_SHADOW_END); >>> + kasan_mem_to_shadow((void *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_BOTTOM)))); >>> + >>> + kasan_populate_shadow((unsigned long)kasan_mem_to_shadow((void *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_BOTTOM))), >>> + (unsigned long)kasan_mem_to_shadow((void *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_TOP) + PAGE_SIZE)), >> >> What's '+ PAGE_SIZE' for? >> > > __fix_to_virt(..._TOP) returns the address of the *bottom* of the last > cpu_entry_area page. +PAGE_SIZE returns one past the end of the > region, which I assume is the correct thing to pass. >
Right.
Perhaps, it would be better to use variables, just avoid such awfully long lines, I mean like this: fixmap_shadow_start = (void *)__fix_to_virt(FIX_CPU_ENTRY_AREA_BOTTOM); fixmap_shadow_start = kasan_mem_to_shadow(fixmap_shadow_start);
fixmap_shadow_end = (void *)__fix_to_virt(FIX_CPU_ENTRY_AREA_TOP) + PAGE_SIZE; fixmap_shadow_end = kasan_mem_to_shadow(fixmap_shadow_end);
kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END), fixmap_shadow_start);
kasan_populate_shadow((unsigned long)fixmap_shadow_start, (unsigned long)fixmap_shadow_end, 0);
I'm also thinking that we should change kasan_populate_shadow() to take void* instead of 'unsigned long' to avoid those casts.
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