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Date: Fri, 31 Dec 2010 14:25:36 +0000
From: "Serge E. Hallyn" <serge@hallyn.com>
To: Hillf Danton <dhillf@gmail.com>
Cc: linux-kernel@vger.kernel.org, "Serge E. Hallyn" <serge@hallyn.com>,
        Linus Torvalds <torvalds@linux-foundation.org>, stable@kernel.org
Subject: Re: [PATCH] fix freeing user_struct in user cache
Message-ID: <20101231142536.GB22593@mail.hallyn.com>
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Quoting Hillf Danton (dhillf@gmail.com):
> When racing on adding into user cache, the new allocated from mm slab
> is freed without putting user namespace.
> 
> Since the user namespace is already operated by getting, putting has
> to be issued.
> 
> Signed-off-by: Hillf Danton <dhillf@gmail.com>

which was previously

> Acked-by: Serge Hallyn <serge@hallyn.com>

thanks again, Hillf.

> ---
> 
> --- a/kernel/user.c	2010-11-01 19:54:12.000000000 +0800
> +++ b/kernel/user.c	2010-12-23 20:42:00.000000000 +0800
> @@ -158,6 +158,7 @@ struct user_struct *alloc_uid(struct use
>  		spin_lock_irq(&uidhash_lock);
>  		up = uid_hash_find(uid, hashent);
>  		if (up) {
> +			put_user_ns(ns);
>  			key_put(new->uid_keyring);
>  			key_put(new->session_keyring);
>  			kmem_cache_free(uid_cachep, new);