{"id":"CVE-2024-58098","summary":"bpf: track changes_pkt_data property for global functions","details":"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 'p' can't 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.","modified":"2026-04-02T12:25:31.415702Z","published":"2025-05-05T14:53:32.417Z","related":["SUSE-SU-2025:01964-1","SUSE-SU-2025:01965-1","SUSE-SU-2025:02000-1","SUSE-SU-2025:02254-1","SUSE-SU-2025:02307-1","SUSE-SU-2025:02333-1","SUSE-SU-2025:02923-1","SUSE-SU-2025:20408-1","SUSE-SU-2025:20413-1","SUSE-SU-2025:20419-1","SUSE-SU-2025:20421-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/58xxx/CVE-2024-58098.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1d572c60488b52882b719ed273767ee3b280413d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/51081a3f25c742da5a659d7fc6fd77ebfdd555be"},{"type":"WEB","url":"https://git.kernel.org/stable/c/79751e9227a5910c0e5a2c7186877d91821d957d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/58xxx/CVE-2024-58098.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-58098"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"51c39bb1d5d105a02e29aa7960f0a395086e6342"},{"fixed":"79751e9227a5910c0e5a2c7186877d91821d957d"},{"fixed":"1d572c60488b52882b719ed273767ee3b280413d"},{"fixed":"51081a3f25c742da5a659d7fc6fd77ebfdd555be"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-58098.json"}}],"schema_version":"1.7.5"}