In the Linux kernel, the following vulnerability has been resolved: pfcp: make sure the SEID is…

Why it is Amber

• CVSS 7.3 high
• Remotely exploitable without logging in
• On your watchlist: linux kernel

References

• https://git.kernel.org/stable/c/23609bce9e1de525d1d0e73fc68c6e7971d0b49e
• https://git.kernel.org/stable/c/2fb6d05f706d79bbdc88835be2f4f45ab56dd819
• https://git.kernel.org/stable/c/3192a5e398c64d48aad64a09e29643e327369bc4
• https://git.kernel.org/stable/c/b18a6496495495e2dc27e525aa3315a0c59b9513

Original description

In the Linux kernel, the following vulnerability has been resolved: pfcp: make sure the SEID is linear before reading it pfcp_encap_recv() only makes sure that the UDP header and the 4 byte PFCP header are in the linear area. When the S flag is set, pfcp_session_recv() then reads the 8 byte SEID that follows, which is not covered by the pskb_may_pull() check. A short PFCP packet with the S flag set, or one whose session header lies in a fragment, therefore makes pfcp_session_recv() read beyond the end of the packet data, and whatever it finds there is stored in the tunnel metadata that flower later classifies on. Pull up to the end of the SEID before reading it, and drop packets that are too short to contain it. Reload the header pointer afterwards since pskb_may_pull() may reallocate the skb head. Use offsetofend() rather than sizeof(struct pfcphdr_session): the structure is not packed, so its size is 16 bytes because of the alignment of the __be64 member, while the header on the wire is only 12 bytes, and valid session messages would be dropped.