CVE-2025-68725

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Do not let BPF test infra emit invalid GSO types to stack Yinhao et al. reported that their fuzzer tool was able to trigger a skb_warn_bad_offload() from netif_skb_features() -> gso_features_check(). When a BPF program - triggered via BPF test infra - pushes the packet to the loopback device via bpf_clone_redirect() then mentioned offload warning can be seen. GSO-related features are then rightfully disabled. We get into this situation due to convert___skb_to_skb() setting gso_segs and gso_size but not gso_type. Technically, it makes sense that this warning triggers since the GSO properties are malformed due to the gso_type. Potentially, the gso_type could be marked non-trustworthy through setting it at least to SKB_GSO_DODGY without any other specific assumptions, but that also feels wrong given we should not go further into the GSO engine in the first place. The checks were added in 121d57af308d ("gso: validate gso_type in GSO handlers") because there were malicious (syzbot) senders that combine a protocol with a non-matching gso_type. If we would want to drop such packets, gso_features_check() currently only returns feature flags via netif_skb_features(), so one location for potentially dropping such skbs could be validate_xmit_unreadable_skb(), but then otoh it would be an additional check in the fast-path for a very corner case. Given bpf_clone_redirect() is the only place where BPF test infra could emit such packets, lets reject them right there.

PUBLISHED Reserved 2025-12-24 | Published 2025-12-24 | Updated 2026-02-09 | Assigner Linux

Product status

References

git.kernel.org/...c/bb7902ed7d7f6d6a7c6c4dc25410d6127ce1085f

git.kernel.org/...c/e0ffb64a2d72c6705b4a4c9efef600409f7e98a0

git.kernel.org/...c/768376ece7036ecb8604961793a1b72afe6345dd

git.kernel.org/...c/8670b53b8ee91f028f7240531064020b7413c461

git.kernel.org/...c/0f3a60869ca22024dfb9c6fce412b0c70cb4ea36

git.kernel.org/...c/fbea4c63b5385588cb44ab21f91e55e33c719a54

git.kernel.org/...c/04a899573fb87273a656f178b5f920c505f68875

cve.org (CVE-2025-68725)

nvd.nist.gov (CVE-2025-68725)

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