On 8/24/20 7:00 AM, Stephen Smalley wrote:

On Fri, Aug 21, 2020 at 9:00 PM Lakshmi Ramasubramanian

quoted

+int security_read_policy_kernel(struct selinux_state *state,
+                               void **data, size_t *len)
+{
+       int rc;
+
+       rc = security_read_policy_len(state, len);
+       if (rc)
+               return rc;
+
+       *data = vmalloc(*len);
+       if (!*data)
+               return -ENOMEM;

+       return security_read_selinux_policy(state, data, len);
  }

See the discussion here:
https://lore.kernel.org/selinux/20200824113015.1375857-1-omosnace@redhat.com/T/#t (local)

In order for this to be safe, you need to ensure that all callers of
security_read_policy_kernel() have taken fsi->mutex in selinuxfs and
any use of security_read_policy_len() occurs while holding the mutex.
Otherwise, the length can change between security_read_policy_len()
and security_read_selinux_policy() if policy is reloaded.

Thanks. I'll make this change.

  -lakshmi