Re: [PATCH v6 00/12] extend task comm from 16 to 24

[Kees Cook]

On Mon, Oct 25, 2021 at 05:05:03PM -0400, Steven Rostedt wrote:
> On Mon, 25 Oct 2021 11:10:09 -0700
> Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote:
> 
> > It looks like a churn that doesn't really address the problem.
> > If we were to allow long names then make it into a pointer and use 16 byte
> > as an optimized storage for short names. Any longer name would be a pointer.
> > In other words make it similar to dentry->d_iname.
> 
> That would be quite a bigger undertaking too, as it is assumed throughout
> the kernel that the task->comm is TASK_COMM_LEN and is nul terminated. And
> most locations that save the comm simply use a fixed size string of
> TASK_COMM_LEN. Not saying its not feasible, but it would require a lot more
> analysis of the impact by changing such a fundamental part of task struct
> from a static to something requiring allocation.
> 
> Unless you are suggesting that we truncate like normal the 16 byte names
> (to a max of 15 characters), and add a way to hold the entire name for
> those locations that understand it.

Agreed -- this is a small change for what is already an "uncommon"
corner case. I don't think this needs to suddenly become an unbounded
string. :)

-- 
Kees Cook