CVE-2026-97921
In the Linux kernel, the following vulnerability has been resolved:
tracing: Free histogram the field rejected for a bad modifier
Writing a hist trigger whose value or variable carries a modifier that is not allowed there leaks the fields that were built for it.
__create_val_field() takes the field from parse_expr() and stores it in hist_data->fields[] only after the modifier checks have run:
Both checks jump past that store, and the err label returns without freeing anything. The error unwinds to create_hist_data(), which calls destroy_hist_data() -> destroy_hist_fields(), and that reaches a field only by walking fields[]. A field that never got there is unreachable.
Leer descripción completaMostrar menos
commit e0213434fe3e ("tracing: Do not let histogram values have some modifiers") set ret to -EINVAL and fell through to the store, which left the field owned by fields[] and freed along with the rest of hist_data. Splitting the check into a value case and a variable case replaced that fall-through with a goto that skips it.
With CONFIG_DEBUG_KMEMLEAK, 200 writes of
each correctly rejected with -EINVAL, leave 332 unreferenced objects (63744 bytes) reported at create_hist_field(); 200 install and remove cycles of a valid trigger leave none. A '.log2' field is two allocations, since create_hist_field() puts the plain field in operands[0] of the log2 field, and both are reported.
Use destroy_hist_field() rather than __destroy_hist_field() so that operands[0] is freed as well. It returns early for HIST_FIELD_FL_VAR_REF, which is what an operand owned by hist_data->var_refs[] needs; the rejected field itself is never a var ref, because a var ref never carries a modifier flag.
Detalles técnicos trazas, registros y código del informe original
hist_field = parse_expr(hist_data, file, field_str, flags, var_name,
&n_subexprs);
...
if (hist_field->flags & HIST_FIELD_FL_VAR) {
if (hist_field->flags & (...))
goto err;
} else {
if (hist_field->flags & (...))
goto err;
}
hist_data->fields[val_idx] = hist_field;
# echo 'hist:keys=prev_pid:vals=next_pid.log2' > \
events/sched/sched_switch/triggerCVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71
- https://git.kernel.org/stable/c/3d42fed18b2c5707b6332ebe87b789fd768eb01b
- https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6
- https://git.kernel.org/stable/c/a2652fcf96b63e9da04951e4e58e6a0672df695d
- https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652
- https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-97921",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7403630eb94c1d664fb873f967427ef2f6ee3699",
"lessThan": "a2652fcf96b63e9da04951e4e58e6a0672df695d",
"versionType": "git"
},
{
"status": "affected",
"version": "e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c",
"lessThan": "3d42fed18b2c5707b6332ebe87b789fd768eb01b",
"versionType": "git"
},
{
"status": "affected",
"version": "e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c",
"lessThan": "e787361bb6b0026ea3eb4d3fa7a304c7fcb99555",
"versionType": "git"
},
{
"status": "affected",
"version": "e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c",
"lessThan": "b22dc0add7d72b8bd9cae3188db0dd65da1c8652",
"versionType": "git"
},
{
"status": "affected",
"version": "e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c",
"lessThan": "891c21f6d5673b2a519b536243bfc6dd2d35beb6",
"versionType": "git"
},
{
"status": "affected",
"version": "e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c",
"lessThan": "230234d12ce42ab04132a32c3a848f07a5d27a71",
"versionType": "git"
},
{
"status": "affected",
"version": "8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad",
"versionType": "git"
},
{
"status": "affected",
"version": "6.1.33",
"lessThan": "6.1.189",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.3.7",
"lessThan": "6.4",
"versionType": "semver"
}
],
"programFiles": [
"kernel/trace/trace_events_hist.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.4"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.4",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.111",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.7",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/trace/trace_events_hist.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-25T11:17:19.160",
"references": [
{
"url": "https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/3d42fed18b2c5707b6332ebe87b789fd768eb01b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a2652fcf96b63e9da04951e4e58e6a0672df695d",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"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."
}
],
"lastModified": "2026-10-03T11:18:09.800",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}