Re: [PATCH v2 4/6] sched: Extend task command name to 64 bytes

[André Almeida]

Em 27/05/2026 05:42, David Laight escreveu:
> On Tue, 26 May 2026 12:31:03 -0400
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> > On Mon, 25 May 2026 11:42:41 +0100
> > David Laight <david.laight.linux@xxxxxxxxx> wrote:
> >
> > > > >   	error = security_task_prctl(option, arg2, arg3, arg4, arg5);
> > > > > @@ -2601,16 +2601,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
> > > > >   			error = -EINVAL;
> > > > >   		break;
> > > > >   	case PR_SET_NAME:
> > > > > -		comm[sizeof(me->comm) - 1] = 0;
> > > > > +		comm[TASK_COMM_LEN - 1] = 0;
> > > > >   		if (strncpy_from_user(comm, (char __user *)arg2,
> > > > > -				      sizeof(me->comm) - 1) < 0)
> > > > > +				      TASK_COMM_LEN - 1) < 0)
> > > >
> > > > Nak - you can't do that.
> > > > You are reading data that the application doesn't expect you to read.
> > >
> > > Or have I got confused over the names...
> >
> > You may have gotten confused by names, as sizeof(me->comm) is the same as
> > TASK_COMM_LEN. Basically, the above doesn't change anything.
>
> The name of the patch doesn't help:
> 	sched: Extend task command name to 64 bytes

well, I will try to make it clear next time :)


> If you want to catch/check all the uses I suspect that all the
> occurrences of TASK_COMM_LEN need changing.
> For clarity this one should probably be TASK_COMM_LEN_OLD.
> (that might be problematic for the uapi headers)

That works for me as well, and I don't see TASK_COMM_LEN being used at 
include/uapi/.

> -- David
>
> > -- Steve