[patch 098/262] kasan: arm64: fix pcpu_page_first_chunk crash with KASAN_VMALLOC

Andrew Morton
2021-11-05T20:39:50Z

From: Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: kasan: arm64: fix pcpu_page_first_chunk crash with KASAN_VMALLOC

With KASAN_VMALLOC and NEED_PER_CPU_PAGE_FIRST_CHUNK, it crashes,

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.

[wangkefeng.wang@huawei.com: fix redefinition of 'kasan_populate_early_vm_area_shadow']
Link: https://lkml.kernel.org/r/20211011123211.3936196-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20210910053354.26721-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Marco Elver <elver@google.com> [KASAN]
Acked-by: Andrey Konovalov <andreyknvl@gmail.com> [KASAN]
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

arch/arm64/mm/kasan_init.c | 16 ++++++++++++++++
include/linux/kasan.h | 6 ++++++
mm/kasan/shadow.c | 5 +++++
mm/vmalloc.c | 1 +
4 files changed, 28 insertions(+)

--- a/arch/arm64/mm/kasan_init.c~kasan-arm64-fix-pcpu_page_first_chunk-crash-with-kasan_vmalloc
+++ a/arch/arm64/mm/kasan_init.c
@@ -287,6 +287,22 @@ static void __init kasan_init_depth(void
init_task.kasan_depth = 0;
}

+#ifdef CONFIG_KASAN_VMALLOC
+void __init 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, NUMA_NO_NODE);
+}
+#endif
+
void __init kasan_init(void)
{
kasan_init_shadow();
--- a/include/linux/kasan.h~kasan-arm64-fix-pcpu_page_first_chunk-crash-with-kasan_vmalloc
+++ a/include/linux/kasan.h
@@ -436,6 +436,8 @@ void kasan_release_vmalloc(unsigned long
unsigned long free_region_start,
unsigned long free_region_end);

+void kasan_populate_early_vm_area_shadow(void *start, unsigned long size);
+
#else /* CONFIG_KASAN_VMALLOC */

static inline int kasan_populate_vmalloc(unsigned long start,
@@ -453,6 +455,10 @@ static inline void kasan_release_vmalloc
unsigned long free_region_start,
unsigned long free_region_end) {}

+static inline void kasan_populate_early_vm_area_shadow(void *start,
+ unsigned long size)
+{ }
+
#endif /* CONFIG_KASAN_VMALLOC */

#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
--- a/mm/kasan/shadow.c~kasan-arm64-fix-pcpu_page_first_chunk-crash-with-kasan_vmalloc
+++ a/mm/kasan/shadow.c
@@ -254,6 +254,11 @@ core_initcall(kasan_memhotplug_init);

#ifdef CONFIG_KASAN_VMALLOC

+void __init __weak kasan_populate_early_vm_area_shadow(void *start,
+ unsigned long size)
+{
+}
+
static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr,
void *unused)
{
--- a/mm/vmalloc.c~kasan-arm64-fix-pcpu_page_first_chunk-crash-with-kasan_vmalloc
+++ a/mm/vmalloc.c
@@ -2291,6 +2291,7 @@ void __init vm_area_register_early(struc
vm->addr = (void *)addr;
vm->next = *p;
*p = vm;
+ kasan_populate_early_vm_area_shadow(vm->addr, vm->size);
}

static void vmap_init_free_space(void)
_