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From: Serge E. Hallyn on 17 Jun 2010 23:50
Quoting Tetsuo Handa (penguin-kernel(a)I-love.SAKURA.ne.jp):
> reparent_to_kthreadd() is calling commit_creds() with tasklist_lock held. But
> commit_creds() calls key_fsuid_changed()/key_fsgid_changed()/proc_id_connector()
> which may sleep. Release tasklist_lock before calling commit_creds().
>
> Signed-off-by: Tetsuo Handa <penguin-kernel(a)I-love.SAKURA.ne.jp>

The reparenting is done in current context, so current_cred can't go
away, and init_cred can't go away. And I can't think of anything
nefarious anyone could do to the task on account of the previous
credentials (as a result of the reparenting) before commit_creds()
completes. So it looks good to me, but David might know of a reason
why it isn't... Anyway:

Acked-by: Serge E. Hallyn <serge(a)hallyn.com>

> ---
> kernel/exit.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- security-testing-2.6.orig/kernel/exit.c
> +++ security-testing-2.6/kernel/exit.c
> @@ -348,8 +348,8 @@ static void reparent_to_kthreadd(void)
> sizeof(current->signal->rlim));
>
> atomic_inc(&init_cred.usage);
> - commit_creds(&init_cred);
> write_unlock_irq(&tasklist_lock);
> + commit_creds(&init_cred);
> }
>
> void __set_special_pids(struct pid *pid)
> --
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