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Subject[PATCH v3 0/5] arm64: kasan: support CONFIG_KASAN_VMALLOC
Date

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.

----------- vmalloc_shadow_start
| |
| |
| | <= non-mapping
| |
| |
|-----------|
|///////////|<- kimage shadow with page table mapping.
|-----------|
| |
| | <= non-mapping
| |
------------- vmalloc_shadow_end
|00000000000|
|00000000000| <= Zero shadow
|00000000000|
------------- KASAN_SHADOW_END


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 works in Kaslr with CONFIG_RANDOMIZE_MODULE_REGION_FULL
and randomize module region inside vmalloc area.

Also work with VMAP_STACK, thanks Ard for testing it.


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

---
Thanks Will Deacon, Ard Biesheuvel and Andrey Konovalov
for reviewing and suggestion.

v3 -> v2
rebase on 5.11-rc6
1. remove always true condition in kasan_init() and remove unsed
vmalloc_shadow_start.
2. select KASAN_VMALLOC if KANSAN_GENERIC is enabled
for VMAP_STACK.
3. tweak commit message

v2 -> v1
1. kasan_init.c tweak indent
2. change Kconfig depends only on HAVE_ARCH_KASAN
3. support randomized module region.


v2:
https://lkml.org/lkml/2021/1/9/49
v1:
https://lore.kernel.org/lkml/20210103171137.153834-1-lecopzer@gmail.com/
---
Lecopzer Chen (5):
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
arm64: Kconfig: select KASAN_VMALLOC if KANSAN_GENERIC is enabled

arch/arm64/Kconfig | 2 ++
arch/arm64/kernel/kaslr.c | 18 ++++++++++--------
arch/arm64/kernel/module.c | 16 +++++++++-------
arch/arm64/mm/kasan_init.c | 24 ++++++++++++++++--------
4 files changed, 37 insertions(+), 23 deletions(-)

--
2.25.1

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