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| author | Eric W. Biederman <ebiederm@xmission.com> | 2012-12-20 19:26:06 -0800 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2012-12-24 22:53:14 -0800 |
| commit | 8382fcac1b813ad0a4e68a838fc7ae93fa39eda0 (patch) | |
| tree | a484c6a712a7361a07d9514ea86f835b70ad3414 | |
| parent | a49f0d1ea3ec94fc7cf33a7c36a16343b74bd565 (diff) | |
| download | lwn-8382fcac1b813ad0a4e68a838fc7ae93fa39eda0.tar.gz lwn-8382fcac1b813ad0a4e68a838fc7ae93fa39eda0.zip | |
pidns: Outlaw thread creation after unshare(CLONE_NEWPID)
The sequence:
unshare(CLONE_NEWPID)
clone(CLONE_THREAD|CLONE_SIGHAND|CLONE_VM)
Creates a new process in the new pid namespace without setting
pid_ns->child_reaper. After forking this results in a NULL
pointer dereference.
Avoid this and other nonsense scenarios that can show up after
creating a new pid namespace with unshare by adding a new
check in copy_prodcess.
Pointed-out-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| -rw-r--r-- | kernel/fork.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index a31b823b3c2d..65ca6d27f24e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1166,6 +1166,14 @@ static struct task_struct *copy_process(unsigned long clone_flags, current->signal->flags & SIGNAL_UNKILLABLE) return ERR_PTR(-EINVAL); + /* + * If the new process will be in a different pid namespace + * don't allow the creation of threads. + */ + if ((clone_flags & (CLONE_VM|CLONE_NEWPID)) && + (task_active_pid_ns(current) != current->nsproxy->pid_ns)) + return ERR_PTR(-EINVAL); + retval = security_task_create(clone_flags); if (retval) goto fork_out; |