FKIE_CVE-2026-98065

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-10-19 10:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject key-less BTF for hash maps map_check_btf() allows a key-less BTF (btf_key_type_id == 0) only for maps that have a ->map_check_btf callback, and leaves the actual decision to that callback. Hash maps used to have no ->map_check_btf, so a key-less BTF was rejected outright. That changed when htab and rhtab gained a ->map_check_btf to register a dtor - htab in commit 1df97a7453ee ("bpf: Register dtor for freeing special fields") and rhtab in commit 6905f8601298 ("bpf: Allow special fields in resizable hashtab"). Neither looks at the key, so a key-less hash map now passes map_check_btf() and gets created. Reading it back through bpffs feeds the key type_id 0 into btf_type_seq_show(); btf_type_by_id() returns the void type, kind_ops[BTF_KIND_UNKN] is NULL, and btf_type_show() dereferences it: RIP: 0010:btf_type_show+0x223/0x2e0 kernel/bpf/btf.c:8232 RSP: 0018:ffffc9000399f868 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000028 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: ffffc9000399f970 R11: 0000000000000001 R12: ffffffff9b96b140 R13: ffffc9000399f8e0 R14: ffff88803d393c00 R15: 0000000000000003 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000000 CR3: 000000003d213000 CR4: 0000000000352ef0 DR0: 0000000039ae8f55 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: <TASK> btf_type_seq_show_flags+0xca/0x120 kernel/bpf/btf.c:8250 htab_map_seq_show_elem+0x12e/0x350 kernel/bpf/hashtab.c:1669 map_seq_show+0x13d/0x1e0 kernel/bpf/inode.c:293 traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112 traverse fs/seq_file.c:99 [inline] seq_read_iter+0x93f/0x1270 fs/seq_file.c:196 seq_read+0x344/0x4d0 fs/seq_file.c:163 vfs_read+0x1e4/0xb40 fs/read_write.c:572 ksys_pread64 fs/read_write.c:764 [inline] __do_sys_pread64 fs/read_write.c:772 [inline] __se_sys_pread64 fs/read_write.c:769 [inline] __x64_sys_pread64+0x1eb/0x250 fs/read_write.c:769 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f Reject a key-less BTF in htab_map_check_btf() and rhtab_map_check_btf(), restoring the previous behavior.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0895a0c0734703be5532f3883c42db95615fd98b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/54098e3fe34ec190bc256b338b9a93c7e2dc9354
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7ca231252820c47aaec42a5db580db98f9b64724
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fa047f2a025003f5654ebd76539f16a6ead0401a
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "54098e3fe34ec190bc256b338b9a93c7e2dc9354",
              "status": "affected",
              "version": "451a84a3ad3c897c03181af433e7c98640730f1f",
              "versionType": "git"
            },
            {
              "lessThan": "fa047f2a025003f5654ebd76539f16a6ead0401a",
              "status": "affected",
              "version": "51a17f0ce19c4ee2a25cf16c93490d509b1ebb0a",
              "versionType": "git"
            },
            {
              "lessThan": "7ca231252820c47aaec42a5db580db98f9b64724",
              "status": "affected",
              "version": "1df97a7453eec80c1912c2d0360290a3970a7671",
              "versionType": "git"
            },
            {
              "lessThan": "0895a0c0734703be5532f3883c42db95615fd98b",
              "status": "affected",
              "version": "1df97a7453eec80c1912c2d0360290a3970a7671",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject key-less BTF for hash maps\n\nmap_check_btf() allows a key-less BTF (btf_key_type_id == 0) only for\nmaps that have a -\u003emap_check_btf callback, and leaves the actual\ndecision to that callback. Hash maps used to have no -\u003emap_check_btf,\nso a key-less BTF was rejected outright.\n\nThat changed when htab and rhtab gained a -\u003emap_check_btf to register a\ndtor - htab in commit 1df97a7453ee (\"bpf: Register dtor for freeing\nspecial fields\") and rhtab in commit 6905f8601298 (\"bpf: Allow special\nfields in resizable hashtab\"). Neither looks at the key, so a key-less\nhash map now passes map_check_btf() and gets created. Reading it back\nthrough bpffs feeds the key type_id 0 into btf_type_seq_show();\nbtf_type_by_id() returns the void type, kind_ops[BTF_KIND_UNKN] is NULL,\nand btf_type_show() dereferences it:\n\nRIP: 0010:btf_type_show+0x223/0x2e0 kernel/bpf/btf.c:8232\nRSP: 0018:ffffc9000399f868 EFLAGS: 00010206\nRAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000\nRDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000028\nRBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000\nR10: ffffc9000399f970 R11: 0000000000000001 R12: ffffffff9b96b140\nR13: ffffc9000399f8e0 R14: ffff88803d393c00 R15: 0000000000000003\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000200000000000 CR3: 000000003d213000 CR4: 0000000000352ef0\nDR0: 0000000039ae8f55 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cTASK\u003e\n btf_type_seq_show_flags+0xca/0x120 kernel/bpf/btf.c:8250\n htab_map_seq_show_elem+0x12e/0x350 kernel/bpf/hashtab.c:1669\n map_seq_show+0x13d/0x1e0 kernel/bpf/inode.c:293\n traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112\n traverse fs/seq_file.c:99 [inline]\n seq_read_iter+0x93f/0x1270 fs/seq_file.c:196\n seq_read+0x344/0x4d0 fs/seq_file.c:163\n vfs_read+0x1e4/0xb40 fs/read_write.c:572\n ksys_pread64 fs/read_write.c:764 [inline]\n __do_sys_pread64 fs/read_write.c:772 [inline]\n __se_sys_pread64 fs/read_write.c:769 [inline]\n __x64_sys_pread64+0x1eb/0x250 fs/read_write.c:769\n do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]\n do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nReject a key-less BTF in htab_map_check_btf() and rhtab_map_check_btf(),\nrestoring the previous behavior."
    }
  ],
  "id": "CVE-2026-98065",
  "lastModified": "2026-10-19T10:18:01.150",
  "metrics": {},
  "published": "2026-09-25T11:17:35.553",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0895a0c0734703be5532f3883c42db95615fd98b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/54098e3fe34ec190bc256b338b9a93c7e2dc9354"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7ca231252820c47aaec42a5db580db98f9b64724"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fa047f2a025003f5654ebd76539f16a6ead0401a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}



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