CVE-2026-98647 (GCVE-0-2026-98647)
Vulnerability from cvelistv5
Published
2026-10-18 15:20
Modified
2026-10-19 09:23
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix divide-by-zero in btf_struct_walk() When an access goes past the struct and the last member is a flexible array, btf_struct_walk() folds the offset back into a single element with (off - moff) % t->size, but never checks that the element type has a size. BTF takes an empty struct, so this in program BTF /* event could be empty */ struct event { #ifdef HAVE_TIMESTAMP __u64 ts; #endif }; struct batch { int nr; struct event events[]; }; divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a sleepable program. Oops: divide error: 0000 [#1] SMP KASAN PTI RIP: 0010:btf_struct_walk+0x53f/0x1570 Call Trace: <TASK> btf_struct_access+0x42a/0xcd0 check_ptr_to_btf_access+0x4dc/0x1160 check_mem_access+0x3a45/0x8740 check_load_mem+0x36a/0xd10 do_check_common+0x3ef0/0xb210 bpf_check+0x6d3b/0x8580 bpf_prog_load+0xf7c/0x2720 __sys_bpf+0xa83/0x3690 __x64_sys_bpf+0xc7/0x150 x64_sys_call+0x1f3f/0x27e0 do_syscall_64+0xe5/0x610 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> Reject a zero-sized element type. The fixed array path in the same function already bails out on the same thing: btf_struct_walk() ... /* skip empty array */ if (moff == mtrue_end) continue; msize /= total_nelems;
References
Impacted products
Vendor Product Version
Linux Linux Version: 9c5f8a1008a121e4c6b24af211034e24b0b63081
Version: 9c5f8a1008a121e4c6b24af211034e24b0b63081
Version: 9c5f8a1008a121e4c6b24af211034e24b0b63081
Version: 9c5f8a1008a121e4c6b24af211034e24b0b63081
Version: 9c5f8a1008a121e4c6b24af211034e24b0b63081
Version: 9c5f8a1008a121e4c6b24af211034e24b0b63081
Version: 9c5f8a1008a121e4c6b24af211034e24b0b63081
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/btf.c"
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          "vendor": "Linux",
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              "version": "6.6.158",
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            },
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              "version": "6.18.55",
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            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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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: Fix divide-by-zero in btf_struct_walk()\n\nWhen an access goes past the struct and the last member is a flexible\narray, btf_struct_walk() folds the offset back into a single element with\n(off - moff) % t-\u003esize, but never checks that the element type has a size.\n\nBTF takes an empty struct, so this in program BTF\n\n\t/* event could be empty */\n\tstruct event {\n #ifdef HAVE_TIMESTAMP\n\t\t__u64 ts;\n #endif\n\t};\n\n\tstruct batch {\n\t\tint nr;\n\t\tstruct event events[];\n\t};\n\ndivides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that\nis not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a\nsleepable program.\n\nOops: divide error: 0000 [#1] SMP KASAN PTI\nRIP: 0010:btf_struct_walk+0x53f/0x1570\nCall Trace:\n \u003cTASK\u003e\n btf_struct_access+0x42a/0xcd0\n check_ptr_to_btf_access+0x4dc/0x1160\n check_mem_access+0x3a45/0x8740\n check_load_mem+0x36a/0xd10\n do_check_common+0x3ef0/0xb210\n bpf_check+0x6d3b/0x8580\n bpf_prog_load+0xf7c/0x2720\n __sys_bpf+0xa83/0x3690\n __x64_sys_bpf+0xc7/0x150\n x64_sys_call+0x1f3f/0x27e0\n do_syscall_64+0xe5/0x610\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n \u003c/TASK\u003e\n\nReject a zero-sized element type. The fixed array path in the same function\nalready bails out on the same thing:\n\n\tbtf_struct_walk()\n\t...\n\t\t/* skip empty array */\n\t\tif (moff == mtrue_end)\n\t\t\tcontinue;\n\n\t\tmsize /= total_nelems;"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:23:16.870Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1ea3820937f8022e044c41c6e95c84b02741b45f"
        },
        {
          "url": "https://git.kernel.org/stable/c/172756f02663ad45c889c001c1a8cb4082a01a05"
        },
        {
          "url": "https://git.kernel.org/stable/c/934e9ba9f8d05656a48624710be67ca4dc8482e6"
        },
        {
          "url": "https://git.kernel.org/stable/c/63af086cb5fa6f72fd924f86bea4c2194da663a2"
        },
        {
          "url": "https://git.kernel.org/stable/c/8eb4cd72daad3a9ee63d2281bbdd16ce6d9406b1"
        },
        {
          "url": "https://git.kernel.org/stable/c/b8fa56722e9c43bcd59c51fe4c7edd5f4158a11b"
        },
        {
          "url": "https://git.kernel.org/stable/c/b0b3dc66529676228cb938cbcad66920f735c223"
        }
      ],
      "title": "bpf: Fix divide-by-zero in btf_struct_walk()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98647",
    "datePublished": "2026-10-18T15:20:18.360Z",
    "dateReserved": "2026-09-25T10:25:14.362Z",
    "dateUpdated": "2026-10-19T09:23:16.870Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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