Re: [PATCH v2 0/4] arm64: kasan: support CONFIG_KASAN_VMALLOC

Ard Biesheuvel
2021-02-03T18:32:41Z

On Sat, 9 Jan 2021 at 11:33, Lecopzer Chen <lecopzer@gmail.com> wrote:
>
> Linux supports KAsan for VMALLOC since commit 3c5c3cfb9ef4da9
> ("kasan: support backing vmalloc space with real shadow memory")
>
> Acroding to how x86 ported it [1], they early allocated p4d and pgd,
> but in arm64 I just simulate how KAsan supports MODULES_VADDR in arm64
> by not to populate the vmalloc area except for kimg address.
>
> Test environment:
> 4G and 8G Qemu virt,
> 39-bit VA + 4k PAGE_SIZE with 3-level page table,
> test by lib/test_kasan.ko and lib/test_kasan_module.ko
>
> It also works in Kaslr with CONFIG_RANDOMIZE_MODULE_REGION_FULL
> and randomize module region inside vmalloc area.
>
>
> [1]: commit 0609ae011deb41c ("x86/kasan: support KASAN_VMALLOC")
>
> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
> Acked-by: Andrey Konovalov <andreyknvl@google.com>
> Tested-by: Andrey Konovalov <andreyknvl@google.com>
>
>
> v2 -> v1
> 1. kasan_init.c tweak indent
> 2. change Kconfig depends only on HAVE_ARCH_KASAN
> 3. support randomized module region.
>
> v1:
> https://lore.kernel.org/lkml/20210103171137.153834-1-lecopzer@gmail.com/
>
> Lecopzer Chen (4):
> arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC
> arm64: kasan: abstract _text and _end to KERNEL_START/END
> arm64: Kconfig: support CONFIG_KASAN_VMALLOC
> arm64: kaslr: support randomized module area with KASAN_VMALLOC
>

I failed to realize that VMAP_STACK and KASAN are currently mutually
exclusive on arm64, and that this series actually fixes that, which is
a big improvement, so it would make sense to call that out.

This builds and runs fine for me on a VM running under KVM.

Tested-by: Ard Biesheuvel <ardb@kernel.org>