{"schema":"threatline.record/2","record":{"id":"CVE-2026-97921","aliases":[],"summary":"tracing: Free histogram the field rejected for a bad modifier","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->fields[] 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&n_subexprs);\n\t...\n\tif (hist_field->flags & HIST_FIELD_FL_VAR) {\n\t\tif (hist_field->flags & (...))\n\t\t\tgoto err;\n\t} else {\n\t\tif (hist_field->flags & (...))\n\t\t\tgoto err;\n\t}\n\n\thist_data->fields[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() -> 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' > \\\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->var_refs[] needs; the\nrejected field itself is never a var ref, because a var ref never carries\na modifier flag.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","source_modified_at":"2026-10-19T09:10:48.148Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"7403630eb94c1d664fb873f967427ef2f6ee3699","lessThan":"a2652fcf96b63e9da04951e4e58e6a0672df695d","status":"affected","versionType":"git"},{"version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","lessThan":"3d42fed18b2c5707b6332ebe87b789fd768eb01b","status":"affected","versionType":"git"},{"version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","lessThan":"e787361bb6b0026ea3eb4d3fa7a304c7fcb99555","status":"affected","versionType":"git"},{"version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","lessThan":"b22dc0add7d72b8bd9cae3188db0dd65da1c8652","status":"affected","versionType":"git"},{"version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","lessThan":"891c21f6d5673b2a519b536243bfc6dd2d35beb6","status":"affected","versionType":"git"},{"version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","lessThan":"230234d12ce42ab04132a32c3a848f07a5d27a71","status":"affected","versionType":"git"},{"version":"8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad","status":"affected","versionType":"git"},{"version":"6.1.33","lessThan":"6.1.189","status":"affected","versionType":"semver"},{"version":"6.3.7","lessThan":"6.4","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","source_modified_at":"2026-10-19T09:10:48.148Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"6.4","status":"affected"},{"version":"0","lessThan":"6.4","status":"unaffected","versionType":"semver"},{"version":"6.1.189","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.111","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","source_modified_at":"2026-10-19T09:10:48.148Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"3d42fed18b2c5707b6332ebe87b789fd768eb01b","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","source_modified_at":"2026-10-19T09:10:48.148Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"891c21f6d5673b2a519b536243bfc6dd2d35beb6","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","source_modified_at":"2026-10-19T09:10:48.148Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"230234d12ce42ab04132a32c3a848f07a5d27a71","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","source_modified_at":"2026-10-19T09:10:48.148Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"6.1.189","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","source_modified_at":"2026-10-19T09:10:48.148Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"6.4","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00205,"percentile":0.10034,"score_date":"2026-10-23"},"published_at":"2026-09-25T10:22:41.081Z","modified_at":"2026-10-19T09:10:48.148Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:10:48.148Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-97921","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/a2652fcf96b63e9da04951e4e58e6a0672df695d"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/3d42fed18b2c5707b6332ebe87b789fd768eb01b"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T09:10:48.148Z","content_hash":"f9623801bcd0f7d5a17e1f68d4adb6034e620fc63c2e53e4f3d8de6a4eeff232"}}