{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c"
            },
            {
              "fixed": "e787361bb6b0026ea3eb4d3fa7a304c7fcb99555"
            },
            {
              "fixed": "b22dc0add7d72b8bd9cae3188db0dd65da1c8652"
            },
            {
              "fixed": "891c21f6d5673b2a519b536243bfc6dd2d35beb6"
            },
            {
              "fixed": "230234d12ce42ab04132a32c3a848f07a5d27a71"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "7403630eb94c1d664fb873f967427ef2f6ee3699"
            },
            {
              "last_affected": "8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "6.1.33"
            },
            {
              "fixed": "6.2"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "6.3.7"
            },
            {
              "fixed": "6.4"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.4.0"
            },
            {
              "fixed": "6.12.111"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.53"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97921.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Free histogram the field rejected for a bad modifier\n\nWriting a hist trigger whose value or variable carries a modifier that is\nnot allowed there leaks the fields that were built for it.\n\n__create_val_field() takes the field from parse_expr() and stores it in\nhist_data-\u003efields[] only after the modifier checks have run:\n\n\thist_field = parse_expr(hist_data, file, field_str, flags, var_name,\n\t\t\t\t\u0026n_subexprs);\n\t...\n\tif (hist_field-\u003eflags \u0026 HIST_FIELD_FL_VAR) {\n\t\tif (hist_field-\u003eflags \u0026 (...))\n\t\t\tgoto err;\n\t} else {\n\t\tif (hist_field-\u003eflags \u0026 (...))\n\t\t\tgoto err;\n\t}\n\n\thist_data-\u003efields[val_idx] = hist_field;\n\nBoth checks jump past that store, and the err label returns without\nfreeing anything. The error unwinds to create_hist_data(), which calls\ndestroy_hist_data() -\u003e destroy_hist_fields(), and that reaches a field\nonly by walking fields[]. A field that never got there is unreachable.\n\ncommit e0213434fe3e (\"tracing: Do not let histogram values have some\nmodifiers\") set ret to -EINVAL and fell through to the store, which left\nthe field owned by fields[] and freed along with the rest of hist_data.\nSplitting the check into a value case and a variable case replaced that\nfall-through with a goto that skips it.\n\nWith CONFIG_DEBUG_KMEMLEAK, 200 writes of\n\n  # echo 'hist:keys=prev_pid:vals=next_pid.log2' \u003e \\\n\t events/sched/sched_switch/trigger\n\neach correctly rejected with -EINVAL, leave 332 unreferenced objects\n(63744 bytes) reported at create_hist_field(); 200 install and remove\ncycles of a valid trigger leave none. A '.log2' field is two\nallocations, since create_hist_field() puts the plain field in\noperands[0] of the log2 field, and both are reported.\n\nUse destroy_hist_field() rather than __destroy_hist_field() so that\noperands[0] is freed as well. It returns early for HIST_FIELD_FL_VAR_REF,\nwhich is what an operand owned by hist_data-\u003evar_refs[] needs; the\nrejected field itself is never a var ref, because a var ref never carries\na modifier flag.",
  "id": "CVE-2026-97921",
  "modified": "2026-09-27T03:30:40.172449093Z",
  "published": "2026-09-25T10:22:41.081Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97921.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97921"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "tracing: Free histogram the field rejected for a bad modifier"
}