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

[Bernd Edlinger]

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.