Linux-libre 4.5-gnu

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index cf038c7d9..cab7a5be4 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -120,6 +120,7 @@ static void __init cpu_set_ttbr1(unsigned long ttbr1)
 void __init kasan_init(void)
 {
 	struct memblock_region *reg;
+	int i;
 
 	/*
 	 * We are going to perform proper setup of shadow memory.
@@ -155,6 +156,14 @@ void __init kasan_init(void)
 				pfn_to_nid(virt_to_pfn(start)));
 	}
 
+	/*
+	 * KAsan may reuse the contents of kasan_zero_pte directly, so we
+	 * should make sure that it maps the zero page read-only.
+	 */
+	for (i = 0; i < PTRS_PER_PTE; i++)
+		set_pte(&kasan_zero_pte[i],
+			pfn_pte(virt_to_pfn(kasan_zero_page), PAGE_KERNEL_RO));
+
 	memset(kasan_zero_page, 0, PAGE_SIZE);
 	cpu_set_ttbr1(__pa(swapper_pg_dir));
 	flush_tlb_all();