> On Nov 13, 2018, at 5:51 PM, Isaac J. Manjarres <isa...@codeaurora.org> wrote:
>
> diff --git a/mm/usercopy.c b/mm/usercopy.c
> index 852eb4e..0293645 100644
> --- a/mm/usercopy.c
> +++ b/mm/usercopy.c
> @@ -151,7 +151,7 @@ static inline void check_bogus_address(const unsigned
> long ptr, unsigned long n,
> bool to_user)
> {
> /* Reject if object wraps past end of memory. */
> - if (ptr + n < ptr)
> + if (ptr + (n - 1) < ptr)
> usercopy_abort("wrapped address", NULL, to_user, 0, ptr + n);
I'm being paranoid, but is it possible this routine could ever be passed "n"
set to zero?
If so, it will erroneously abort indicating a wrapped address as (n - 1) wraps
to ULONG_MAX.
Easily fixed via:
if ((n != 0) && (ptr + (n - 1) < ptr))
William Kucharski