pidfd: Use new infrastructure to fix deadlocks in execve
This changes __pidfd_fget to use the new exec_update_mutex instead of cred_guard_mutex. This should be safe, as the credentials do not change before exec_update_mutex is locked. Therefore whatever file access is possible with holding the cred_guard_mutex here is also possbile with the exec_update_mutex. Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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@ -577,7 +577,7 @@ static struct file *__pidfd_fget(struct task_struct *task, int fd)
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struct file *file;
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int ret;
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ret = mutex_lock_killable(&task->signal->cred_guard_mutex);
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ret = mutex_lock_killable(&task->signal->exec_update_mutex);
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if (ret)
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return ERR_PTR(ret);
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@ -586,7 +586,7 @@ static struct file *__pidfd_fget(struct task_struct *task, int fd)
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else
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file = ERR_PTR(-EPERM);
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mutex_unlock(&task->signal->cred_guard_mutex);
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mutex_unlock(&task->signal->exec_update_mutex);
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return file ?: ERR_PTR(-EBADF);
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}
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