Re: [PATCH] mm/mprotect: Fix do_mprotect_pkey() limit check

[Lorenzo Stoakes <lstoakes@gmail.com>]

On Tue, Jun 06, 2023 at 02:29:12PM -0400, Liam R. Howlett wrote:
> The return of do_mprotect_pkey() can still be incorrectly returned as
> success if there is a gap that spans to or beyond the end address passed
> in.  Update the check to ensure that the end address has indeed been
> seen.
>
> Link: https://lore.kernel.org/all/CABi2SkXjN+5iFoBhxk71t3cmunTk-s=rB4T7qo0UQRh17s49PQ@mail.gmail.com/
> Fixes: 82f951340f25 ("mm/mprotect: fix do_mprotect_pkey() return on error")
> Reported-by: Jeff Xu <jeffxu@chromium.org>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
> ---
>  mm/mprotect.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 92d3d3ca390a..c59e7561698c 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -867,7 +867,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  	}
>  	tlb_finish_mmu(&tlb);
>
> -	if (!error && vma_iter_end(&vmi) < end)
> +	if (!error && tmp < end)
>  		error = -ENOMEM;
>
>  out:
> --
> 2.39.2
>

As discussed via irc, was able to confirm locally this fixes the reported
issue, so have a quick:-

Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>