Re: [PATCH v4 2/5] connector: use __get_task_comm in proc_comm_connector

[Steven Rostedt]

On Wed, 13 Oct 2021 10:23:43 +0000
Yafang Shao <laoar.shao@xxxxxxxxx> wrote:

> --- a/drivers/connector/cn_proc.c
> +++ b/drivers/connector/cn_proc.c
> @@ -230,7 +230,10 @@ void proc_comm_connector(struct task_struct *task)
>  	ev->what = PROC_EVENT_COMM;
>  	ev->event_data.comm.process_pid  = task->pid;
>  	ev->event_data.comm.process_tgid = task->tgid;
> -	get_task_comm(ev->event_data.comm.comm, task);
> +
> +	/* This may get truncated. */
> +	__get_task_comm(ev->event_data.comm.comm,
> +			sizeof(ev->event_data.comm.comm), task);
>  
>  	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
>  	msg->ack = 0; /* not used */

__get_task_comm() uses strncpy() which my understanding is, does not add
the nul terminating byte when truncating. Which changes the functionality
here. As all task comms have a terminating byte, the old method would copy
that and include it. This won't add the terminating byte if the buffer is
smaller than the comm, and that might cause issues.

-- Steve