From 29970dc24faf0078beb4efab5455b4f504d2198d Mon Sep 17 00:00:00 2001 From: Hailong Liu Date: Tue, 12 Jan 2021 15:49:14 -0800 Subject: arm/kasan: fix the array size of kasan_early_shadow_pte[] MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The size of kasan_early_shadow_pte[] now is PTRS_PER_PTE which defined to 512 for arm. This means that it only covers the prev Linux pte entries, but not the HWTABLE pte entries for arm. The reason it currently works 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 is always right with different compiler/linker, or if more bss symbols are 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 poisoned it after kasan_early_init(). Then enabled CONFIG_KASAN, it failed to boot up. Link: https://lkml.kernel.org/r/20210109044622.8312-1-hailongliiu@yeah.net Signed-off-by: Hailong Liu Signed-off-by: Ziliang Guo Reviewed-by: Linus Walleij Cc: Andrey Ryabinin Cc: Russell King Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Ard Biesheuvel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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) { -- cgit v1.2.3-58-ga151