Hi Ard,

On Fri, 8 Jan 2021 at 19:31, Andrey Konovalov [off-list ref] wrote:

quoted

On Sun, Jan 3, 2021 at 6:12 PM Lecopzer Chen [off-list ref] wrote:

quoted

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,
but not test for HW_TAG(I have no proper device), thus keep
HW_TAG and KASAN_VMALLOC mutual exclusion until confirming
the functionality.


[1]: commit 0609ae011deb41c ("x86/kasan: support KASAN_VMALLOC")

Signed-off-by: Lecopzer Chen <redacted>

Hi Lecopzer,

Thanks for working on this!

Acked-by: Andrey Konovalov <redacted>
Tested-by: Andrey Konovalov <redacted>

for the series along with the other two patches minding the nit in patch #3.

Will, Catalin, could you please take a look at the arm changes?

Thanks!

If vmalloc can now be backed with real shadow memory, we no longer
have to keep the module region in its default location when KASLR and
KASAN are both enabled.

So the check on line 164 in arch/arm64/kernel/kaslr.c should probably
be updated to reflect this change.

I've tested supporting module region randomized and It looks fine
in some easy test(insmod some modules).

I'll add this to patch v2, thanks for your suggestion.

BRs,
Lecopzer
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