Re: [PATCH v2] sanitize task->comm to avoid leaking escape codes

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> > This patch sanitizes task->comm to only contain printable characters
> > when it is set.  Additionally, it redefines get_task_comm so that it is
> > more obvious when misused by callers (presently nothing was incorrectly
> > calling get_task_comm's unsafe use of strncpy).
> 
> This is a regression for tools that correctly handle unmutilated data.
> 
> > +	/* sanitize non-printable characters */
> > +	for (i = 0; buf[i] && i < (sizeof(tsk->comm) - 1); i++) {
> > +		if (!isprint(buf[i]))
> > +			tsk->comm[i] = '?';
> 
> The kernel "isprint" isn't adequate for this. comm is set by the shell
> based on argv[0] usually which means that in normal situations it is a
> UTF-8 string.

Ah, I recall one use case. In past, some IBM folks talked about they
want to map Java thread name to prctl(PR_SET_NAME). In such case, 
utf-8 name is very common.

So, I agree with you.

Thanks.