[PATCH v11 13/13] powerpc/32s: map kasan zero shadow with PAGE_READONLY instead of PAGE_KERNEL_RO
flat view
STALE2727d
From: Christophe Leroy <hidden>
Date: 2019-04-26 16:24:05
Also in:
linux-mm
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
For hash32, the zero shadow page gets mapped with PAGE_READONLY instead of PAGE_KERNEL_RO, because the PP bits don't provide a RO kernel, so PAGE_KERNEL_RO is equivalent to PAGE_KERNEL. By using PAGE_READONLY, the page is RO for both kernel and user, but this is not a security issue as it contains only zeroes. Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/mm/kasan/kasan_init_32.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index ba8361487075..0d62be3cba47 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c@@ -39,7 +39,10 @@ static int kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_ if (!new) return -ENOMEM; - kasan_populate_pte(new, PAGE_KERNEL_RO); + if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) + kasan_populate_pte(new, PAGE_READONLY); + else + kasan_populate_pte(new, PAGE_KERNEL_RO); pmd_populate_kernel(&init_mm, pmd, new); } return 0;
@@ -84,7 +87,10 @@ static int __ref kasan_init_region(void *start, size_t size) static void __init kasan_remap_early_shadow_ro(void) { - kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO); + if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) + kasan_populate_pte(kasan_early_shadow_pte, PAGE_READONLY); + else + kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO); flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END); }
--
2.13.3