{"id":"CVE-2026-97921","revision":"c3bf09fc68b04a26a3fab7a4597c6bcf","records":[{"revision":"c3bf09fc68b04a26a3fab7a4597c6bcf","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-97921","aliases":[],"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":0,"publishedAt":"2026-09-25T10:22:41.081+00:00","modifiedAt":"2026-10-19T09:10:48.148+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/trace/trace_events_hist.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"7403630eb94c1d664fb873f967427ef2f6ee3699\",\n                            \"lessThan\": \"a2652fcf96b63e9da04951e4e58e6a0672df695d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c\",\n                            \"lessThan\": \"3d42fed18b2c5707b6332ebe87b789fd768eb01b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c\",\n                            \"lessThan\": \"e787361bb6b0026ea3eb4d3fa7a304c7fcb99555\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c\",\n                            \"lessThan\": \"b22dc0add7d72b8bd9cae3188db0dd65da1c8652\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c\",\n                            \"lessThan\": \"891c21f6d5673b2a519b536243bfc6dd2d35beb6\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c\",\n                            \"lessThan\": \"230234d12ce42ab04132a32c3a848f07a5d27a71\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8d505d06d7330f5d67d3e5e9e1c647fb0b10ddad\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"6.1.33\",\n                            \"lessThan\": \"6.1.189\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.3.7\",\n                            \"lessThan\": \"6.4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/trace/trace_events_hist.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.4\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.4\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.189\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.158\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.111\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.53\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.7\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/a2652fcf96b63e9da04951e4e58e6a0672df695d","https://git.kernel.org/stable/c/3d42fed18b2c5707b6332ebe87b789fd768eb01b","https://git.kernel.org/stable/c/e787361bb6b0026ea3eb4d3fa7a304c7fcb99555","https://git.kernel.org/stable/c/b22dc0add7d72b8bd9cae3188db0dd65da1c8652","https://git.kernel.org/stable/c/891c21f6d5673b2a519b536243bfc6dd2d35beb6","https://git.kernel.org/stable/c/230234d12ce42ab04132a32c3a848f07a5d27a71"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-97921","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-97921","identifiers":["CVE-2026-97921"]},"retained":false,"historicalAffected":[]}],"coverage":[]}