After kasan_init() executed, no one is allowed to write to kasan_zero_page,
so write protect it.
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
---
arch/x86/mm/kasan_init_64.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 303e470..1b1110f 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -125,10 +125,16 @@ void __init kasan_init(void)
/*
* kasan_zero_page has been used as early shadow memory, thus it may
- * contain some garbage. Now we can clear it, since after the TLB flush
- * no one should write to it.
+ * contain some garbage. Now we can clear and write protect it, since
+ * after the TLB flush no one should write to it.
*/
memset(kasan_zero_page, 0, PAGE_SIZE);
+ for (i = 0; i < PTRS_PER_PTE; i++) {
+ pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO);
+ set_pte(&kasan_zero_pte[i], pte);
+ }
+ /* Flush TLBs again to be sure that write protection applied. */
+ __flush_tlb_all();
init_task.kasan_depth = 0;
pr_info("KernelAddressSanitizer initialized\n");
--
2.4.10
--
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