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SubjectRe: [PATCH] fix freeing user_struct in user cache
On Thu, Dec 23, 2010 at 08:52:34PM +0800, Hillf Danton wrote:
> 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.
>
> btw, it could be freed out of lock?
>
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> ---
>
> --- 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);

Hm, are you sure about this? Also, why send this to me, did I last
touch this?

confused,

greg k-h


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