linux-kernel - Re: [PATCH] exec: Move io_uring_task_cancel after the point of no return

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Message-ID: <87lfegcjxm.fsf@x220.int.ebiederm.org>
Date:   Wed, 02 Dec 2020 09:21:57 -0600
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     <linux-kernel@...r.kernel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Al Viro <viro@...IV.linux.org.uk>,
        Kees Cook <keescook@...omium.org>, Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH] exec: Move io_uring_task_cancel after the point of no return

ebiederm@...ssion.com (Eric W. Biederman) writes:

> Now that unshare_files happens in begin_new_exec after the point of no
> return, io_uring_task_cancel can also happen later.
>
> Effectively this means io_uring activities for a task are only canceled
> when exec succeeds.
>
> Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
> ---
>
> This is against my exec-for-v5.11 branch

applied.

>  fs/exec.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 14fae2ec1c9d..9e9368603168 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1257,6 +1257,11 @@ int begin_new_exec(struct linux_binprm * bprm)
>  	if (retval)
>  		goto out;
>  
> +	/*
> +	 * Cancel any io_uring activity across execve
> +	 */
> +	io_uring_task_cancel();
> +
>  	/* Ensure the files table is not shared. */
>  	retval = unshare_files();
>  	if (retval)
> @@ -1783,11 +1788,6 @@ static int bprm_execve(struct linux_binprm *bprm,
>  	struct file *file;
>  	int retval;
>  
> -	/*
> -	 * Cancel any io_uring activity across execve
> -	 */
> -	io_uring_task_cancel();
> -
>  	retval = prepare_bprm_creds(bprm);
>  	if (retval)
>  		return retval;