Commit 626ac545 authored by Serge E. Hallyn's avatar Serge E. Hallyn Committed by Linus Torvalds
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user namespace: fix copy_user_ns return value

When a CONFIG_USER_NS=n and a user tries to unshare some namespace other
than the user namespace, the dummy copy_user_ns returns NULL rather than
the old_ns.

This value then gets assigned to task->nsproxy->user_ns, so that a
subsequent setuid, which uses task->nsproxy->user_ns, causes a NULL
pointer deref.

Fix this by returning old_ns.

Signed-off-by: default avatarSerge E. Hallyn <>
Signed-off-by: default avatarLinus Torvalds <>
parent 9550b105
......@@ -49,7 +49,7 @@ static inline struct user_namespace *copy_user_ns(int flags,
if (flags & CLONE_NEWUSER)
return ERR_PTR(-EINVAL);
return NULL;
return old_ns;
static inline void put_user_ns(struct user_namespace *ns)
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