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

[David Laight]

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

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)

-- David

> 
> -- Steve