To optimize the performance of struct page initialization,
vmemmap_populate() will no longer zero memory.
We must explicitly zero the memory that is allocated by vmemmap_populate()
for kasan, as this memory does not go through struct page initialization
path.
Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: Steven Sistare <steven.sistare@xxxxxxxxxx>
Reviewed-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Reviewed-by: Bob Picco <bob.picco@xxxxxxxxxx>
---
arch/x86/mm/kasan_init_64.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 02c9d7553409..7d06cf0b0b6e 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -84,6 +84,28 @@ static struct notifier_block kasan_die_notifier = {
};
#endif
+/*
+ * Memory that was allocated by vmemmap_populate is not zeroed, so we must
+ * zero it here explicitly.
+ */
+static void
+zero_vemmap_populated_memory(void)
+{
+ u64 i, start, end;
+
+ for (i = 0; i < E820_MAX_ENTRIES && pfn_mapped[i].end; i++) {
+ void *kaddr_start = pfn_to_kaddr(pfn_mapped[i].start);
+ void *kaddr_end = pfn_to_kaddr(pfn_mapped[i].end);
+
+ start = (u64)kasan_mem_to_shadow(kaddr_start);
+ end = (u64)kasan_mem_to_shadow(kaddr_end);
+ memset((void *)start, 0, end - start);
+ }
+ start = (u64)kasan_mem_to_shadow(_stext);
+ end = (u64)kasan_mem_to_shadow(_end);
+ memset((void *)start, 0, end - start);
+}
+
void __init kasan_early_init(void)
{
int i;
@@ -156,6 +178,13 @@ void __init kasan_init(void)
pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO);
set_pte(&kasan_zero_pte[i], pte);
}
+
+ /*
+ * vmemmap_populate does not zero the memory, so we need to zero it
+ * explicitly
+ */
+ zero_vemmap_populated_memory();
+
/* Flush TLBs again to be sure that write protection applied. */
__flush_tlb_all();
--
2.13.4
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