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

On Thu, Aug 10, 2023 at 12:21:28PM -0700, Axel Rasmussen 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@arm.com Closes: https://lore.kernel.org/linux-mm/8fbb5965-28f7-4e9a-ac04-1406ed8fc2d4@arm.co... Signed-off-by: Axel Rasmussen axelrasmussen@google.com

Acked-by: Peter Xu peterx@redhat.com