Re: [PATCH 0/5] Infrastructure to allow fixing exec deadlocks

Bernd Edlinger
2020-03-09T13:58:21Z

On 3/8/20 10:34 PM, Eric W. Biederman wrote:
>
> Bernd, everyone
>
> This is how I think the infrastructure change should look that makes way
> for fixing this issue.
>
> - Cleanup and reorder the code so code that can potentially wait
> indefinitely for userspace comes at the beginning for flush_old_exec.
> - Add a new mutex and take it after we have passed any potential
> indefinite waits for userspace.
>
> Then I think it is just going through the existing users of
> cred_guard_mutex and fixing them to use the new one.
>
> There really aren't that many users of cred_guard_mutex so we should be
> able to get through the easy ones fairly quickly. And anything that
> isn't easy we can wait until we have a good fix.
>
> The users of cred_guard_mutex that I saw were:
> fs/proc/base.c:
> proc_pid_attr_write
> do_io_accounting
> proc_pid_stack
> proc_pid_syscall
> proc_pid_personality
>
> perf_event_open
> mm_access
> kcmp
> pidfd_fget
> seccomp_set_mode_filter
>
> Bernd I think I have addressed the issues you pointed out in v1.
> Please let me know if you see anything else.
>

Yes, looks good, except some nits.

Thanks
Bernd.