Re: [PATCH] pid: sys_wait... fixes

[Eric W. Biederman]

Oleg Nesterov <oleg@xxxxxxxxxx> writes:

> On 12/05, Eric W. Biederman wrote:
>> 
>> This modifies do_wait and eligible_child to take a pair of
>> enum pid_type and struct pid *pid to precisely specify what
>> set of processes are eligible to be waited for,  instead of the
>> raw pid_t value from sys_wait4.
>
> Personally, I like this patch very much. Not only it fixes the bug,
> in my opinion it also makes the code more clean.
>
> However at first glance it has a minor fixable problem,
>
>> +	if (type < PIDTYPE_MAX) {
>> +		if (p->pids[type].pid != pid)
>>  			return 0;
>>  	}
>
> If type != PIDTYPE_PID we can't trust p->pids[type].pid unless p is a
> group leader. This .pid could be just a "random value".

Ugh.  You are correct.  Thanks for the review.
That is one annoying special case.

Eric
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