In the Linux kernel, the following vulnerability has been resolved:
openvswitch: fix GSO userspace truncation underflow
OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb length in OVS_CB(skb)->cutlen. When a later userspace action segments a GSO skb, queue_gso_packets() reuses that delta for each smaller segment. A segment can then reach queue_userspace_packet() with cutlen greater than skb->len, underflowing the length passed to skb_zerocopy().
Store the maximum preserved length instead and bound each consumer against the current skb length. Use U32_MAX as the no-truncation sentinel so the value remains valid if skb geometry changes before a consumer handles it.
References
- https://git.kernel.org/stable/c/100a23b1613e9218e0af654ef102352c713f0263
- https://git.kernel.org/stable/c/4032f8ed10fcb84d41c508dfb04be96589f78dfe
- https://git.kernel.org/stable/c/a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855
- https://git.kernel.org/stable/c/ea85dbcbe8d4056ecb54352f97743d138ea4c407
- https://git.kernel.org/stable/c/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc