[PATCH -next 3/3] kasan: arm64: Fix pcpu_page_first_chunk crash with KASAN_VMALLOC

Kefeng Wang
2021-07-05T11:08:03Z

With KASAN_VMALLOC and NEED_PER_CPU_PAGE_FIRST_CHUNK, it crashs,

Unable to handle kernel paging request at virtual address ffff7000028f2000
...
swapper pgtable: 64k pages, 48-bit VAs, pgdp=0000000042440000
[ffff7000028f2000] pgd=000000063e7c0003, p4d=000000063e7c0003, pud=000000063e7c0003, pmd=000000063e7b0003, pte=0000000000000000
Internal error: Oops: 96000007 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.13.0-rc4-00003-gc6e6e28f3f30-dirty #62
Hardware name: linux,dummy-virt (DT)
pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO BTYPE=--)
pc : kasan_check_range+0x90/0x1a0
lr : memcpy+0x88/0xf4
sp : ffff80001378fe20
...
Call trace:
kasan_check_range+0x90/0x1a0
pcpu_page_first_chunk+0x3f0/0x568
setup_per_cpu_areas+0xb8/0x184
start_kernel+0x8c/0x328

The vm area used in vm_area_register_early() has no kasan shadow memory,
Let's add a new kasan_populate_early_vm_area_shadow() function to populate
the vm area shadow memory to fix the issue.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
arch/arm64/mm/kasan_init.c | 18 ++++++++++++++++++
include/linux/kasan.h | 2 ++
mm/kasan/init.c | 5 +++++
mm/vmalloc.c | 1 +
4 files changed, 26 insertions(+)

diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 61b52a92b8b6..c295a256c573 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -287,6 +287,24 @@ static void __init kasan_init_depth(void)
init_task.kasan_depth = 0;
}

+#ifdef CONFIG_KASAN_VMALLOC
+void __init __weak kasan_populate_early_vm_area_shadow(void *start,
+ unsigned long size)
+{
+ unsigned long shadow_start, shadow_end;
+
+ if (!is_vmalloc_or_module_addr(start))
+ return;
+
+ shadow_start = (unsigned long)kasan_mem_to_shadow(start);
+ shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
+ shadow_end = (unsigned long)kasan_mem_to_shadow(start + size);
+ shadow_end = ALIGN(shadow_end, PAGE_SIZE);
+ kasan_map_populate(shadow_start, shadow_end,
+ early_pfn_to_nid(virt_to_pfn(start)));
+}
+#endif
+
void __init kasan_init(void)
{
kasan_init_shadow();
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 5310e217bd74..79d3895b0240 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -49,6 +49,8 @@ extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
int kasan_populate_early_shadow(const void *shadow_start,
const void *shadow_end);

+void kasan_populate_early_vm_area_shadow(void *start, unsigned long size);
+
static inline void *kasan_mem_to_shadow(const void *addr)
{
return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index cc64ed6858c6..d39577d088a1 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -279,6 +279,11 @@ int __ref kasan_populate_early_shadow(const void *shadow_start,
return 0;
}

+void __init __weak kasan_populate_early_vm_area_shadow(void *start,
+ unsigned long size)
+{
+}
+
static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
{
pte_t *pte;
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a98cf97f032f..f19e07314ee5 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2249,6 +2249,7 @@ void __init vm_area_register_early(struct vm_struct *vm, size_t align)
vm->addr = (void *)addr;

vm_area_add_early(vm);
+ kasan_populate_early_vm_area_shadow(vm->addr, vm->size);
}

static void vmap_init_free_space(void)
--
2.26.2