CVE-2021-47223

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: bridge: fix vlan tunnel dst null pointer dereference<br /> <br /> This patch fixes a tunnel_dst null pointer dereference due to lockless<br /> access in the tunnel egress path. When deleting a vlan tunnel the<br /> tunnel_dst pointer is set to NULL without waiting a grace period (i.e.<br /> while it&amp;#39;s still usable) and packets egressing are dereferencing it<br /> without checking. Use READ/WRITE_ONCE to annotate the lockless use of<br /> tunnel_id, use RCU for accessing tunnel_dst and make sure it is read<br /> only once and checked in the egress path. The dst is already properly RCU<br /> protected so we don&amp;#39;t need to do anything fancy than to make sure<br /> tunnel_id and tunnel_dst are read only once and checked in the egress path.