Because the kasan_zero_page(which is used as the shadow
region for some memory that KASan doesn't need to track.) won't be writen
after kasan_init, so change the mapping of kasan_zero_page into readonly.
Cc: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
---
arch/arm/mm/kasan_init.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c
index 7cfdc39..c11826a 100644
--- a/arch/arm/mm/kasan_init.c
+++ b/arch/arm/mm/kasan_init.c
@@ -200,6 +200,7 @@ void __init kasan_init(void)
{
struct memblock_region *reg;
u64 orig_ttbr0;
+ int i;
orig_ttbr0 = cpu_get_ttbr(0);
@@ -243,6 +244,17 @@ void __init kasan_init(void)
create_mapping((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
(unsigned long)kasan_mem_to_shadow((void *)(PKMAP_BASE+PMD_SIZE)),
NUMA_NO_NODE);
+
+ /*
+ * 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_at(&init_mm, KASAN_SHADOW_START + i*PAGE_SIZE,
+ &kasan_zero_pte[i], pfn_pte(
+ virt_to_pfn(kasan_zero_page),
+ __pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY | L_PTE_XN | L_PTE_RDONLY)));
+ memset(kasan_zero_page, 0, PAGE_SIZE);
cpu_set_ttbr0(orig_ttbr0);
flush_cache_all();
local_flush_bp_all();
--
2.9.0
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
