/proc/<pid>/stat file documentation

/proc/<pid>/stat file documentation

[Szőts Ákos]

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Dear Michael,

I found a documentation deficiency on [1] in /proc/<pid>/stat file (Table 
1-4). May I ask you to indicate in this table that ESP and EIP have non-zero 
values only when the process is exiting or dumping core and the calling 
process has the permission for PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT. 
For implementation reference see [2].

Please, also note that for many of the reported numbers in this table the 
aforementioned permissions are needed to be displayed correctly (as non-
zeroes). They are start_code, end_code, start_stack, esp, eip, wchan, 
start_data, end_data, start_brk, arg_start, arg_end, env_start, env_end, and 
exit_code.

A small addition: I also observed that on [3] the "blog" points to 404.

Thank you and all the best,

Ákos

[1]: https://www.kernel.org/doc/html/latest/filesystems/proc.html
[2]: https://github.com/torvalds/linux/blob/master/fs/proc/array.c#L481-L502
[3]: https://www.kernel.org/doc/man-pages/maintaining.html

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Re: /proc/<pid>/stat file documentation

[Stefan Puiu]

Hi Ákos,

On Mon, Mar 22, 2021 at 10:50 AM Szőts Ákos <szotsaki@gmail.com> wrote:
>
> Dear Michael,
>
> I found a documentation deficiency on [1] in /proc/<pid>/stat file (Table
> 1-4). May I ask you to indicate in this table that ESP and EIP have non-zero
> values only when the process is exiting or dumping core and the calling
> process has the permission for PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT.
> For implementation reference see [2].

You're pointing to the in-kernel documentation (link [1]). As far as I
know, that's not maintained by the man-pages project, so they might
not be able to help with changing that.

The man page for proc is here though:
https://man7.org/linux/man-pages/man5/procfs.5.html, maybe the info
can be added there?

>
> Please, also note that for many of the reported numbers in this table the
> aforementioned permissions are needed to be displayed correctly (as non-
> zeroes). They are start_code, end_code, start_stack, esp, eip, wchan,
> start_data, end_data, start_brk, arg_start, arg_end, env_start, env_end, and
> exit_code.
>
> A small addition: I also observed that on [3] the "blog" points to 404.

I get an SSL error in Firefox ("Secure Connection Failed" and
"PR_END_OF_FILE_ERROR") when trying to click the blog link
(https://blog.man7.org/).

Stefan.

>
> Thank you and all the best,
>
> Ákos
>
> [1]: https://www.kernel.org/doc/html/latest/filesystems/proc.html
> [2]: https://github.com/torvalds/linux/blob/master/fs/proc/array.c#L481-L502
> [3]: https://www.kernel.org/doc/man-pages/maintaining.html