Re: [PATCH v3 3/3] kasan: arm64: Fix pcpu_page_first_chunk crash with KASAN_VMALLOC

From: Kefeng Wang
Date: Mon Aug 09 2021 - 09:35:03 EST



On 2021/8/9 19:21, Marco Elver wrote:
On Mon, 9 Aug 2021 at 13:10, Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:

On 2021/8/9 17:37, Kefeng Wang wrote:
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.
Should add Acked-by: Marco Elver <elver@xxxxxxxxxx> [for KASAN parts] ,
My Ack is still valid, thanks for noting.
Thanks,  Marco ;)