Re: [PATCH] arm/kasan:fix the arry size of kasan_early_shadow_pte
On Tue, 12 Jan 2021 at 07:19, Andrew Morton wrote: > > On Sun, 10 Jan 2021 13:03:49 +0100 Linus Walleij > wrote: > > > On Sun, Jan 10, 2021 at 11:21 AM hailong wrote: > > > > > >> +#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. > > > > > > > > > > I guess not for arm. But I'm not sure for other ARCHs. > > > > Oh it's a generic include. Sorry for the confusion. > > > > All good then! > > > > This code is 2+ years old. Do we think it warrants a cc:stable? > Not needed - ARM only gained Kasan support this cycle, and this patch does not affect any other architectures
Re: [PATCH] arm/kasan:fix the arry size of kasan_early_shadow_pte
On Sun, 10 Jan 2021 13:03:49 +0100 Linus Walleij wrote: > On Sun, Jan 10, 2021 at 11:21 AM hailong wrote: > > > >> +#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. > > > > > > > I guess not for arm. But I'm not sure for other ARCHs. > > Oh it's a generic include. Sorry for the confusion. > > All good then! > This code is 2+ years old. Do we think it warrants a cc:stable?
Re: Re: [PATCH] arm/kasan:fix the arry size of kasan_early_shadow_pte
On Sun, Jan 10, 2021 at 11:21 AM hailong wrote: > >> +#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. > > > > I guess not for arm. But I'm not sure for other ARCHs. Oh it's a generic include. Sorry for the confusion. All good then! Yours, Linus Walleij
Re: [PATCH] arm/kasan:fix the arry size of kasan_early_shadow_pte
On Sat, Jan 9, 2021 at 5:51 AM Hailong liu wrote:
> From: Hailong Liu
>
> 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
> Signed-off-by: Ziliang Guo
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
Yours,
Linus Walleij
Re: [PATCH] arm/kasan:fix the arry size of kasan_early_shadow_pte
(+ Linus)
On Sat, 9 Jan 2021 at 05:50, Hailong liu wrote:
>
> From: Hailong Liu
>
> 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
> Signed-off-by: Ziliang Guo
> ---
> include/linux/kasan.h | 6 +-
> mm/kasan/init.c | 3 ++-
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 5e0655fb2a6f..fe1ae73ff8b5 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -35,8 +35,12 @@ struct kunit_kasan_expectation {
> #define KASAN_SHADOW_INIT 0
> #endif
>
> +#ifndef PTE_HWTABLE_PTRS
> +#define PTE_HWTABLE_PTRS 0
> +#endif
> +
> 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];
> extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD];
> extern pud_t kasan_early_shadow_pud[PTRS_PER_PUD];
> extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
> index bc0ad208b3a7..7ca0b92d5886 100644
> --- a/mm/kasan/init.c
> +++ b/mm/kasan/init.c
> @@ -64,7 +64,8 @@ static inline bool kasan_pmd_table(pud_t pud)
> return false;
> }
> #endif
> -pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss;
> +pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]
> + __page_aligned_bss;
>
> static inline bool kasan_pte_table(pmd_t pmd)
> {
> --
> 2.17.1
>
>
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