tun: add missing verification for short frame

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: tun: add missing verification for short frame The cited commit missed to check against the validity of the frame length in the tun_xdp_one() path, which could cause a corrupted skb to be sent downstack. Even before the skb is transmitted, the tun_xdp_one-->eth_type_trans() may access the Ethernet header although it can be less than ETH_HLEN. Once transmitted, this could either cause out-of-bound access beyond the actual length, or confuse the underlayer with incorrect or inconsistent header length in the skb metadata. In the alternative path, tun_get_user() already prohibits short frame which has the length less than Ethernet header size from being transmitted for IFF_TAP. This is to drop any frame shorter than the Ethernet header size just like how tun_get_user() does. CVE: CVE-2024-41091

References

• https://git.kernel.org/stable/c/32b0aaba5dbc85816898167d9b5d45a22eae82e9
• https://git.kernel.org/stable/c/6100e0237204890269e3f934acfc50d35fd6f319
• https://git.kernel.org/stable/c/589382f50b4a5d90d16d8bc9dcbc0e927a3e39b2
• https://git.kernel.org/stable/c/ad6b3f622ccfb4bfedfa53b6ebd91c3d1d04f146
• https://git.kernel.org/stable/c/d5ad89b7d01ed4e66fd04734fc63d6e78536692a
• https://git.kernel.org/stable/c/a9d1c27e2ee3b0ea5d40c105d6e728fc114470bb
• https://git.kernel.org/stable/c/8418f55302fa1d2eeb73e16e345167e545c598a5
• https://git.kernel.org/stable/c/049584807f1d797fc3078b68035450a9769eb5c3