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SubjectRe: [PATCH v4 2/5] connector: use __get_task_comm in proc_comm_connector
On Wed, Oct 13, 2021 at 10:19 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 13 Oct 2021 10:23:43 +0000
> Yafang Shao <laoar.shao@gmail.com> 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.
>

Right, that is a problem.
It seems that we should add a new helper get_task_comm_may_truncated().

--
Thanks
Yafang

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