Re: [PATCH mm-unstable fix] mm: userfaultfd: check for start + len overflow in validate_range: fix

[Yu Zhao]

On Thu, Aug 10, 2023 at 1:21 PM Axel Rasmussen <axelrasmussen@xxxxxxxxxx> wrote:
>
> A previous fixup to this commit fixed one issue, but introduced another:
> we're now overly strict when validating the src address for UFFDIO_COPY.
>
> Most of the validation in validate_range is useful to apply to src as
> well as dst, but page alignment is only a requirement for dst, not src.
> So, split the function up so src can use an "unaligned" variant, while
> still allowing us to share the majority of the code between the
> different cases.
>
> Reported-by: Ryan Roberts <ryan.roberts@xxxxxxx>
> Closes: https://lore.kernel.org/linux-mm/8fbb5965-28f7-4e9a-ac04-1406ed8fc2d4@xxxxxxx/T/#t
> Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>

Reviewed-by:  Yu Zhao <yuzhao@xxxxxxxxxx>