{"api_version":"1","generated_at":"2026-10-08T16:17:44+00:00","cve":"CVE-2026-97921","urls":{"html":"https://cve.report/CVE-2026-97921","api":"https://cve.report/api/cve/CVE-2026-97921.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-97921","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-97921"},"summary":{"title":"tracing: Free histogram the field rejected for a bad modifier","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:19","updated_at":"2026-10-03 11:18:09"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555","name":"https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71","name":"https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a2652fcf96b63e9da04951e4e58e6a0672df695d","name":"https://git.kernel.org/stable/c/a2652fcf96b63e9da04951e4e58e6a0672df695d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6","name":"https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652","name":"https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3d42fed18b2c5707b6332ebe87b789fd768eb01b","name":"https://git.kernel.org/stable/c/3d42fed18b2c5707b6332ebe87b789fd768eb01b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97921","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97921","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7403630eb94c1d664fb873f967427ef2f6ee3699 a2652fcf96b63e9da04951e4e58e6a0672df695d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c 3d42fed18b2c5707b6332ebe87b789fd768eb01b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c e787361bb6b0026ea3eb4d3fa7a304c7fcb99555 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c b22dc0add7d72b8bd9cae3188db0dd65da1c8652 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c 891c21f6d5673b2a519b536243bfc6dd2d35beb6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c 230234d12ce42ab04132a32c3a848f07a5d27a71 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.33 6.1.189 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.3.7 6.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.4","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.189 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.158 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.111 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"97921","cve":"CVE-2026-97921","epss":"0.002050000","percentile":"0.095680000","score_date":"2026-10-05","updated_at":"2026-10-06 00:14:18"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/trace/trace_events_hist.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a2652fcf96b63e9da04951e4e58e6a0672df695d","status":"affected","version":"7403630eb94c1d664fb873f967427ef2f6ee3699","versionType":"git"},{"lessThan":"3d42fed18b2c5707b6332ebe87b789fd768eb01b","status":"affected","version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","versionType":"git"},{"lessThan":"e787361bb6b0026ea3eb4d3fa7a304c7fcb99555","status":"affected","version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","versionType":"git"},{"lessThan":"b22dc0add7d72b8bd9cae3188db0dd65da1c8652","status":"affected","version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","versionType":"git"},{"lessThan":"891c21f6d5673b2a519b536243bfc6dd2d35beb6","status":"affected","version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","versionType":"git"},{"lessThan":"230234d12ce42ab04132a32c3a848f07a5d27a71","status":"affected","version":"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c","versionType":"git"},{"status":"affected","version":"8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad","versionType":"git"},{"lessThan":"6.1.189","status":"affected","version":"6.1.33","versionType":"semver"},{"lessThan":"6.4","status":"affected","version":"6.3.7","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/trace/trace_events_hist.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.4"},{"lessThan":"6.4","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.189","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.158","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.111","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.189","versionStartIncluding":"6.1.33","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.158","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.111","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.7","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc3","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3.7","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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."}],"providerMetadata":{"dateUpdated":"2026-10-03T11:00:33.908Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a2652fcf96b63e9da04951e4e58e6a0672df695d"},{"url":"https://git.kernel.org/stable/c/3d42fed18b2c5707b6332ebe87b789fd768eb01b"},{"url":"https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555"},{"url":"https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652"},{"url":"https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6"},{"url":"https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71"}],"title":"tracing: Free histogram the field rejected for a bad modifier","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-97921","datePublished":"2026-09-25T10:22:41.081Z","dateReserved":"2026-09-25T10:18:58.202Z","dateUpdated":"2026-10-03T11:00:33.908Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:19","lastModifiedDate":"2026-10-03 11:18:09","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"97921","Ordinal":"1","Title":"tracing: Free histogram the field rejected for a bad modifier","CVE":"CVE-2026-97921","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"97921","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"tracing: Free histogram the field rejected for a bad modifier"}]}}}