fkie_cve-2025-68725
Vulnerability from fkie_nvd
Published
2025-12-24 11:16
Modified
2025-12-24 11:16
Severity ?
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/04a899573fb87273a656f178b5f920c505f68875
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fbea4c63b5385588cb44ab21f91e55e33c719a54
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Do not let BPF test infra emit invalid GSO types to stack\n\nYinhao et al. reported that their fuzzer tool was able to trigger a\nskb_warn_bad_offload() from netif_skb_features() -\u003e gso_features_check().\nWhen a BPF program - triggered via BPF test infra - pushes the packet\nto the loopback device via bpf_clone_redirect() then mentioned offload\nwarning can be seen. GSO-related features are then rightfully disabled.\n\nWe get into this situation due to convert___skb_to_skb() setting\ngso_segs and gso_size but not gso_type. Technically, it makes sense\nthat this warning triggers since the GSO properties are malformed due\nto the gso_type. Potentially, the gso_type could be marked non-trustworthy\nthrough setting it at least to SKB_GSO_DODGY without any other specific\nassumptions, but that also feels wrong given we should not go further\ninto the GSO engine in the first place.\n\nThe checks were added in 121d57af308d (\"gso: validate gso_type in GSO\nhandlers\") because there were malicious (syzbot) senders that combine\na protocol with a non-matching gso_type. If we would want to drop such\npackets, gso_features_check() currently only returns feature flags via\nnetif_skb_features(), so one location for potentially dropping such skbs\ncould be validate_xmit_unreadable_skb(), but then otoh it would be\nan additional check in the fast-path for a very corner case. Given\nbpf_clone_redirect() is the only place where BPF test infra could emit\nsuch packets, lets reject them right there."
    }
  ],
  "id": "CVE-2025-68725",
  "lastModified": "2025-12-24T11:16:01.797",
  "metrics": {},
  "published": "2025-12-24T11:16:01.797",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/04a899573fb87273a656f178b5f920c505f68875"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fbea4c63b5385588cb44ab21f91e55e33c719a54"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}


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