On Sun, 2022-10-16 at 23:10 +0800, Dawei Li wrote:
> find_task_by_pid_ns() is safe if and only if it's under protection
> from rcu read lock, implements the protection.
>
> base-commit: 193cb8372424184dde28088a4230a5fed0afb0ad
>
> Signed-off-by: Dawei Li <set_pte...@outlook.com>
> ---
> arch/um/drivers/mconsole_kern.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
> index 5026e7b9adfe..6b80e766ae80 100644
> --- a/arch/um/drivers/mconsole_kern.c
> +++ b/arch/um/drivers/mconsole_kern.c
> @@ -683,7 +683,10 @@ void mconsole_stack(struct mc_request *req)
> return;
> }
>
> + rcu_read_lock();
> to = find_task_by_pid_ns(pid_requested, &init_pid_ns);
> + rcu_read_unlock();
> +
> if ((to == NULL) || (pid_requested == 0)) {
> mconsole_reply(req, "Couldn't find that pid", 1, 0);
> return;
This can't be right - the 'to' pointer is used later in the code (not in
the existing context), so the protection, if needed, would have to
include the later "with_console()" call?
johannes
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