Re: [PATCH RFC 0/2] Dynamically allocate memory to store task's full name

Kees Cook
2025-03-14T21:25:12Z

On Fri, Mar 14, 2025 at 10:57:13AM +0530, Bhupesh wrote:
> While working with user-space debugging tools which work especially
> on linux gaming platforms, I found that the task name is truncated due
> to the limitation of TASK_COMM_LEN.
>
> For example, currently running 'ps', the task->comm value of a long
> task name is truncated due to the limitation of TASK_COMM_LEN.
> create_very_lon
>
> This leads to the names passed from userland via pthread_setname_np()
> being truncated.

So there have been long discussions about "comm", and it mainly boils
down to "leave it alone". For the /proc-scraping tools like "ps" and
"top", they check both "comm" and "cmdline", depending on mode. The more
useful (and already untruncated) stuff is in "cmdline", so I suspect it
may make more sense to have pthread_setname_np() interact with that
instead. Also TASK_COMM_LEN is basically considered userspace ABI at
this point and we can't sanely change its length without breaking the
world.

Best to use /proc/$pid/task/$tid/cmdline IMO...

-Kees

> will be shown in 'ps'. For example:
> create_very_long_name_user_space_script.sh
>
> Bhupesh (2):
> exec: Dynamically allocate memory to store task's full name
> fs/proc: Pass 'task->full_name' via 'proc_task_name()'
>
> fs/exec.c | 21 ++++++++++++++++++---
> fs/proc/array.c | 2 +-
> include/linux/sched.h | 9 +++++++++
> 3 files changed, 28 insertions(+), 4 deletions(-)
>
> --
> 2.38.1
>

--
Kees Cook