net: fix information leakage in /proc/net/ptype

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: fix information leakage in /proc/net/ptype In one net namespace, after creating a packet socket without binding it to a device, users in other net namespaces can observe the new `packet_type` added by this packet socket by reading `/proc/net/ptype` file. This is minor information leakage as packet socket is namespace aware. Add a net pointer in `packet_type` to keep the net namespace of of corresponding packet socket. In `ptype_seq_show`, this net pointer must be checked when it is not NULL.

References

• https://git.kernel.org/stable/c/8f88c78d24f6f346919007cd459fd7e51a8c7779
• https://git.kernel.org/stable/c/be1ca30331c7923c6f376610c1bd6059be9b1908
• https://git.kernel.org/stable/c/c38023032a598ec6263e008d62c7f02def72d5c7
• https://git.kernel.org/stable/c/b67ad6170c0ea87391bb253f35d1f78857736e54
• https://git.kernel.org/stable/c/e372ecd455b6ebc7720f52bf4b5f5d44d02f2092
• https://git.kernel.org/stable/c/db044d97460ea792110eb8b971e82569ded536c6
• https://git.kernel.org/stable/c/e43669c77cb3a742b7d84ecdc7c68c4167a7709b
• https://git.kernel.org/stable/c/839ec7039513a4f84bfbaff953a9393471176bee
• https://git.kernel.org/stable/c/47934e06b65637c88a762d9c98329ae6e3238888