powerpc/32s: map kasan zero shadow with PAGE_READONLY instead of PAGE_KERNEL_RO (da3a3b0a) · Commits · 戴 / test

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 <christophe.leroy@c-s.fr> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/kasan/kasan_init_32.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -39,6 +39,9 @@ static int kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_

		if (!new)
		return -ENOMEM;
		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);
		}
		@@ -84,6 +87,9 @@ static int __ref kasan_init_region(void *start, size_t size)

		static void __init kasan_remap_early_shadow_ro(void)
		{
		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);

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