Re: [PATCH AUTOSEL 5.19 54/64] ARM: 9202/1: kasan: support CONFIG_KASAN_VMALLOC

Sasha Levin
2022-08-20T14:37:26Z

On Tue, Aug 16, 2022 at 04:45:14PM +0200, Ard Biesheuvel wrote:
>On Sun, 14 Aug 2022 at 17:30, Sasha Levin <sashal@kernel.org> wrote:
>>
>> From: Lecopzer Chen <lecopzer.chen@mediatek.com>
>>
>> [ Upstream commit 565cbaad83d83e288927b96565211109bc984007 ]
>>
>> Simply make shadow of vmalloc area mapped on demand.
>>
>> Since the virtual address of vmalloc for Arm is also between
>> MODULE_VADDR and 0x100000000 (ZONE_HIGHMEM), which means the shadow
>> address has already included between KASAN_SHADOW_START and
>> KASAN_SHADOW_END.
>> Thus we need to change nothing for memory map of Arm.
>>
>> This can fix ARM_MODULE_PLTS with KASan, support KASan for higmem
>> and support CONFIG_VMAP_STACK with KASan.
>>
>> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
>> Tested-by: Linus Walleij <linus.walleij@linaro.org>
>> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
>> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>
>This patch does not belong in -stable. It has no fixes: or cc:stable
>tags, and the contents are completely inappropriate for backporting
>anywhere. In general, I think that no patch that touches arch/arm
>(with the exception of DTS updates, perhaps) should ever be backported
>unless proposed or acked by the maintainer.

I'll drop it.

>I know I shouldn't ask, but how were these patches build/boot tested?
>KAsan is very tricky to get right, especially on 32-bit ARM ...

They were only build tested at this stage. They go through
boot/functional test only after they are actually queued up for the
various trees.

--
Thanks,
Sasha