In the Linux kernel, the following vulnerability has been resolved:
net/sched: cls_flow: Dont expose folded kernel pointers
The flow classifier falls back to addr_fold() for fields that are missing from packet headers. In map mode, userspace controls mask, xor, rshift, addend and divisor, and can observe the resulting classid through class statistics. This allows a tc classifier in a user/network namespace to recover the 32-bit folded value of skb->sk, skb_dst() or skb_nfct().
Align with standard kernel practices for pointer hashing and replace the XOR folding with a keyed siphash (which is cryptographically secure)
References
- https://git.kernel.org/stable/c/0a8b5b74f0e6b6b9ce453bcfa4baa502c4c7577a
- https://git.kernel.org/stable/c/19f2ecf8ea564562c7e7a919cf38068dd9aa1c96
- https://git.kernel.org/stable/c/3d054001860270748405a3f9270c5fa0bf7ffc19
- https://git.kernel.org/stable/c/6151159618198675e01c391676e579738286c135
- https://git.kernel.org/stable/c/f294fc71c4a0fa4964f6428a1b4e7929c1d83125
- https://git.kernel.org/stable/c/fb31fbe51c233f3bf47021121f63d2e42cac2d08