Re: [PATCH] unshare: Use rcu_assign_pointer when setting sighand

[Oleg Nesterov <oleg@tv-sign.ru>]

"Eric W. Biederman" wrote:
> 
> @@ -1573,7 +1573,7 @@ asmlinkage long sys_unshare(unsigned lon
> 
>                 if (new_sigh) {
>                         sigh = current->sighand;
> -                       current->sighand = new_sigh;
> +                       rcu_assign_pointer(current->sighand, new_sigh);
>                         new_sigh = sigh;
>                 }

Isn't it better to just replace this code with
'BUG_ON(new_sigh != NULL)' ?

It is never executed, but totally broken, afaics.
task_lock() has nothing to do with ->sighand changing.

Oleg.
-
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