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

Andrew Morton
2010-06-28T20:01:54Z

On Wed, 23 Jun 2010 23:23:35 +0300
Alexey Dobriyan <adobriyan@gmail.com> wrote:

> On Wed, Jun 23, 2010 at 09:41:45PM +0200, Oleg Nesterov wrote:
> > On 06/23, Kees Cook wrote:
>
> > > -extern char *get_task_comm(char *to, struct task_struct *tsk);
> > > +#define get_task_comm(buf, task) get_task_comm_size(buf, sizeof(buf), task)
> > > +extern char *get_task_comm_size(char *to, size_t len, struct task_struct *tsk);
> >
> > Oh, but this means that get_task_comm(ptr, task) doesn't work?
>
> The number of users is so small, and everyone uses TASK_COMM_LEN,
> so maybe nothing should be done or "char buf[TASK_COMM_LEN]"?

Yup, it would take an act of wilful daftness to pass anything other
than a TASK_COMM_LEN array into get_task_comm().

I can't say I like the patch much - going in and altering a task's
comm[] behind its back seems fraught with all sorts of problems which I
can't immediately think of. Do we corrupt (err, "fix")
/proc/pid/cmdline as well?

Surely it would be better to fix the tools which display this info
rather than making the kernel tell fibs.