Messages in this thread |  | | From | Linus Walleij <> | Date | Sat, 9 Jan 2021 22:26:08 +0100 | Subject | Re: [PATCH] arm/kasan:fix the arry size of kasan_early_shadow_pte |
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On Sat, Jan 9, 2021 at 5:51 AM Hailong liu <hailongliiu@yeah.net> wrote:
> From: Hailong Liu <liu.hailong6@zte.com.cn> > > The size of kasan_early_shadow_pte[] now is PTRS_PER_PTE which defined to > 512 for arm architecture. This means that it only covers the prev Linux pte > entries, but not the HWTABLE pte entries for arm. > > The reason it works well current is that the symbol kasan_early_shadow_page > immediately following kasan_early_shadow_pte in memory is page aligned, > which makes kasan_early_shadow_pte look like a 4KB size array. But we can't > ensure the order always right with different compiler/linker, nor more bss > symbols be introduced. > > We had a test with QEMU + vexpress:put a 512KB-size symbol with attribute > __section(".bss..page_aligned") after kasan_early_shadow_pte, and poison it > after kasan_early_init(). Then enabled CONFIG_KASAN, it failed to boot up. > > Signed-off-by: Hailong Liu <liu.hailong6@zte.com.cn> > Signed-off-by: Ziliang Guo <guo.ziliang@zte.com.cn>
OK I see the problem, I think.
> +#ifndef PTE_HWTABLE_PTRS > +#define PTE_HWTABLE_PTRS 0 > +#endif
Can this even happen? We have either pgtable-2level.h or pgtable-3level.h, both of which define PTE_HWTABLE_PTRS.
> extern unsigned char kasan_early_shadow_page[PAGE_SIZE]; > -extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE]; > +extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS];
Yeah this looks exactly like bm_pte so it makes sense.
If you drop the first ifndef, Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Yours, Linus Walleij
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