[PATCH 2/2] ARM: Clamp MAX_DMA_ADDRESS to 32-bit

[Linus Walleij]

On Thu, Mar 24, 2022 at 6:54 PM Florian Fainelli <f.fainelli at gmail.com> wrote:

> MAX_DMA_ADDRESS is a virtual address, therefore it needs to fit within a
> 32-bit unsigned quantity. Platforms defining a DMA zone size in
> their machine descriptor can easily overflow this quantity depending on
> the DMA zone size and/or the PAGE_OFFSET setting.
>
> In most cases this is harmless, however in the case of a
> CONFIG_DEBUG_VIRTUAL enabled, __virt_addr_valid() will be unable to
> return that MAX_DMA_ADDRESS is valid because the value passed to that
> function is an unsigned long which has already overflowed.
>
> Fixes: e377cd8221eb ("ARM: 8640/1: Add support for CONFIG_DEBUG_VIRTUAL")
> Fixes: 2fb3ec5c9503 ("ARM: Replace platform definition of ISA_DMA_THRESHOLD/MAX_DMA_ADDRESS")
> Signed-off-by: Florian Fainelli <f.fainelli at gmail.com>

Reviewed-by: Linus Walleij <linus.walleij at linaro.org>

Yours,
Linus Walleij