CVE-2024-58098 (GCVE-0-2024-58098)

Vulnerability from cvelistv5 – Published: 2025-05-05 14:53 – Updated: 2025-05-09 08:06
VLAI?
Title
bpf: track changes_pkt_data property for global functions
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: track changes_pkt_data property for global functions When processing calls to certain helpers, verifier invalidates all packet pointers in a current state. For example, consider the following program: __attribute__((__noinline__)) long skb_pull_data(struct __sk_buff *sk, __u32 len) { return bpf_skb_pull_data(sk, len); } SEC("tc") int test_invalidate_checks(struct __sk_buff *sk) { int *p = (void *)(long)sk->data; if ((void *)(p + 1) > (void *)(long)sk->data_end) return TCX_DROP; skb_pull_data(sk, 0); *p = 42; return TCX_PASS; } After a call to bpf_skb_pull_data() the pointer 'p' can't be used safely. See function filter.c:bpf_helper_changes_pkt_data() for a list of such helpers. At the moment verifier invalidates packet pointers when processing helper function calls, and does not traverse global sub-programs when processing calls to global sub-programs. This means that calls to helpers done from global sub-programs do not invalidate pointers in the caller state. E.g. the program above is unsafe, but is not rejected by verifier. This commit fixes the omission by computing field bpf_subprog_info->changes_pkt_data for each sub-program before main verification pass. changes_pkt_data should be set if: - subprogram calls helper for which bpf_helper_changes_pkt_data returns true; - subprogram calls a global function, for which bpf_subprog_info->changes_pkt_data should be set. The verifier.c:check_cfg() pass is modified to compute this information. The commit relies on depth first instruction traversal done by check_cfg() and absence of recursive function calls: - check_cfg() would eventually visit every call to subprogram S in a state when S is fully explored; - when S is fully explored: - every direct helper call within S is explored (and thus changes_pkt_data is set if needed); - every call to subprogram S1 called by S was visited with S1 fully explored (and thus S inherits changes_pkt_data from S1). The downside of such approach is that dead code elimination is not taken into account: if a helper call inside global function is dead because of current configuration, verifier would conservatively assume that the call occurs for the purpose of the changes_pkt_data computation.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 51c39bb1d5d105a02e29aa7960f0a395086e6342 , < 79751e9227a5910c0e5a2c7186877d91821d957d (git)
Affected: 51c39bb1d5d105a02e29aa7960f0a395086e6342 , < 1d572c60488b52882b719ed273767ee3b280413d (git)
Affected: 51c39bb1d5d105a02e29aa7960f0a395086e6342 , < 51081a3f25c742da5a659d7fc6fd77ebfdd555be (git)
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    Linux Linux Affected: 5.6
Unaffected: 0 , < 5.6 (semver)
Unaffected: 6.6.90 , ≤ 6.6.* (semver)
Unaffected: 6.12.25 , ≤ 6.12.* (semver)
Unaffected: 6.13 , ≤ * (original_commit_for_fix)
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          "programFiles": [
            "include/linux/bpf_verifier.h",
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: track changes_pkt_data property for global functions\n\nWhen processing calls to certain helpers, verifier invalidates all\npacket pointers in a current state. For example, consider the\nfollowing program:\n\n    __attribute__((__noinline__))\n    long skb_pull_data(struct __sk_buff *sk, __u32 len)\n    {\n        return bpf_skb_pull_data(sk, len);\n    }\n\n    SEC(\"tc\")\n    int test_invalidate_checks(struct __sk_buff *sk)\n    {\n        int *p = (void *)(long)sk-\u003edata;\n        if ((void *)(p + 1) \u003e (void *)(long)sk-\u003edata_end) return TCX_DROP;\n        skb_pull_data(sk, 0);\n        *p = 42;\n        return TCX_PASS;\n    }\n\nAfter a call to bpf_skb_pull_data() the pointer \u0027p\u0027 can\u0027t be used\nsafely. See function filter.c:bpf_helper_changes_pkt_data() for a list\nof such helpers.\n\nAt the moment verifier invalidates packet pointers when processing\nhelper function calls, and does not traverse global sub-programs when\nprocessing calls to global sub-programs. This means that calls to\nhelpers done from global sub-programs do not invalidate pointers in\nthe caller state. E.g. the program above is unsafe, but is not\nrejected by verifier.\n\nThis commit fixes the omission by computing field\nbpf_subprog_info-\u003echanges_pkt_data for each sub-program before main\nverification pass.\nchanges_pkt_data should be set if:\n- subprogram calls helper for which bpf_helper_changes_pkt_data\n  returns true;\n- subprogram calls a global function,\n  for which bpf_subprog_info-\u003echanges_pkt_data should be set.\n\nThe verifier.c:check_cfg() pass is modified to compute this\ninformation. The commit relies on depth first instruction traversal\ndone by check_cfg() and absence of recursive function calls:\n- check_cfg() would eventually visit every call to subprogram S in a\n  state when S is fully explored;\n- when S is fully explored:\n  - every direct helper call within S is explored\n    (and thus changes_pkt_data is set if needed);\n  - every call to subprogram S1 called by S was visited with S1 fully\n    explored (and thus S inherits changes_pkt_data from S1).\n\nThe downside of such approach is that dead code elimination is not\ntaken into account: if a helper call inside global function is dead\nbecause of current configuration, verifier would conservatively assume\nthat the call occurs for the purpose of the changes_pkt_data\ncomputation."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-09T08:06:08.048Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/79751e9227a5910c0e5a2c7186877d91821d957d"
        },
        {
          "url": "https://git.kernel.org/stable/c/1d572c60488b52882b719ed273767ee3b280413d"
        },
        {
          "url": "https://git.kernel.org/stable/c/51081a3f25c742da5a659d7fc6fd77ebfdd555be"
        }
      ],
      "title": "bpf: track changes_pkt_data property for global functions",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2024-58098",
    "datePublished": "2025-05-05T14:53:32.417Z",
    "dateReserved": "2025-03-06T15:52:09.189Z",
    "dateUpdated": "2025-05-09T08:06:08.048Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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