Re: [PATCH 1/3] userfaultfd: non-cooperative: fix fork fctx->new memleak

[Mike Rapoport <rppt@linux.vnet.ibm.com>]

> From: Mike Rapoport <rppt@linux.vnet.ibm.com>
> 
> We have a memleak in the ->new ctx if the uffd of the parent is closed
> before the fork event is read, nothing frees the new context.
> 
> Reported-by: Andrea Arcangeli <aarcange@redhat.com>

I think
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
would be appropriate here.

> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> ---
>  fs/userfaultfd.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index d2f15a6..5087a69 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -548,6 +548,15 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
>  		if (ACCESS_ONCE(ctx->released) ||
>  		    fatal_signal_pending(current)) {
>  			__remove_wait_queue(&ctx->event_wqh, &ewq->wq);
> +			if (ewq->msg.event == UFFD_EVENT_FORK) {
> +				struct userfaultfd_ctx *new;
> +
> +				new = (struct userfaultfd_ctx *)
> +					(unsigned long)
> +					ewq->msg.arg.reserved.reserved1;
> +
> +				userfaultfd_ctx_put(new);
> +			}
>  			break;
>  		}

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