{"id":"CVE-2026-99140","revision":"ccfb908b8b7446a99b96ece358f85ef9","records":[{"revision":"ccfb908b8b7446a99b96ece358f85ef9","observedAt":"2026-10-30T13:45:33.454+00:00","statement":{"source":"cve-program","id":"CVE-2026-99140","aliases":[],"title":"tracing: Fix hist trigger timestamps for buffered events","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix hist trigger timestamps for buffered events\n\nSyzkaller triggered a WARN_ON_ONCE(!nest) warning:\n\n  WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp\n  Call trace:\n    ring_buffer_event_time_stamp\n    hist_field_timestamp\n    hist_fn_call\n    event_hist_trigger\n    event_triggers_call\n    __event_trigger_test_discard\n    trace_event_buffer_commit\n    do_trace_event_raw_event_sched_switch\n    trace_event_raw_event_sched_switch\n\nThe warning is probabilistically reproducible and is related to syzkaller\nexecuting the following commands:\n\n  echo 'prev_pid == 999999' > events/sched/sched_switch/filter\n  echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger\n\nThe specific triggering process is as follows:\n\nCPU 0                                           CPU 1\n(context switching)                             (echo 'hist:keys=common_timestamp' > \\\n                                                        events/sched/sched_switch/trigger)\ndo_trace_event_raw_event_##call\n  trace_event_buffer_lock_reserve\n    if (!tr->no_filter_buffering_ref &&\n        trace_file->flags & EVENT_FILE_FL_FILTERED)\n        return entry;  // return directly\n                                                event_hist_trigger_parse\n                                                  hist_register_trigger\n                                                    tracing_set_filter_buffering(file->tr, true);\n                                                      tr->no_filter_buffering_ref++;\n    __trace_buffer_lock_reserve\n      rb_start_commit\n        local_inc(&cpu_buffer->committing);  // skipped and not executed\n  trace_event_buffer_commit\n    __event_trigger_test_discard\n      event_triggers_call\n        event_hist_trigger\n          hist_fn_call\n            hist_field_timestamp\n              ring_buffer_event_time_stamp\n                nest = local_read(&cpu_buffer->committing);\n                WARN_ON_ONCE(!nest)  // trigger warning\n\nThe root cause is that when an event file has a filter attached and the\nhist trigger has not yet been attached, trace_event_buffer_lock_reserve()\nwrites the event into the per-CPU trace_buffered_event temp buffer instead\nof reserving it in the ring buffer, so cpu_buffer->committing is not\nincremented. When the event is later processed at commit time by a hist\ntrigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a\nzero committing count, triggering WARN_ON_ONCE(!nest).\n\ntracing_event_time_stamp() was added by commit d8279bfc5e959 (\"tracing:\nAdd tracing_event_time_stamp() API\") for exactly this case: if the event\nis the per-CPU trace_buffered_event, it returns the current ring buffer\ntimestamp. But it never gained a caller. Use it in hist_field_timestamp(),\nso that a hist trigger that races onto a buffered event records the\ncurrent time, which is only marginally later than when the event was\nrecorded, instead of warning and recording a bogus timestamp.","state":0,"publishedAt":"2026-10-28T10:34:51.421+00:00","modifiedAt":"2026-10-30T12:42:12.896+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\": \"b94bc80df64823e676b506f8de7dcf6a688d681e\",\n                            \"lessThan\": \"b3a94a79047d3fc9385b3709cb2b86f4a26ed0c3\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b94bc80df64823e676b506f8de7dcf6a688d681e\",\n                            \"lessThan\": \"71c5c7420478d94d6eb0b427f66fa41bbda651e3\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b94bc80df64823e676b506f8de7dcf6a688d681e\",\n                            \"lessThan\": \"ab320f6aa3769480f735ed0ad026c4a61799b7bc\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b94bc80df64823e676b506f8de7dcf6a688d681e\",\n                            \"lessThan\": \"af192a356e9830a0df231b590ad6fb1fc28c9315\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b94bc80df64823e676b506f8de7dcf6a688d681e\",\n                            \"lessThan\": \"09c7cce2e59e6b3b1807520bcb1980c561f15d1e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b94bc80df64823e676b506f8de7dcf6a688d681e\",\n                            \"lessThan\": \"89e90b16aadd6e66bd0323bc8dfc76a62e756b57\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b94bc80df64823e676b506f8de7dcf6a688d681e\",\n                            \"lessThan\": \"9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\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\": \"5.13\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.13\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.224\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.191\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.161\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.115\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.59\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.13\",\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/b3a94a79047d3fc9385b3709cb2b86f4a26ed0c3","https://git.kernel.org/stable/c/71c5c7420478d94d6eb0b427f66fa41bbda651e3","https://git.kernel.org/stable/c/ab320f6aa3769480f735ed0ad026c4a61799b7bc","https://git.kernel.org/stable/c/af192a356e9830a0df231b590ad6fb1fc28c9315","https://git.kernel.org/stable/c/09c7cce2e59e6b3b1807520bcb1980c561f15d1e","https://git.kernel.org/stable/c/89e90b16aadd6e66bd0323bc8dfc76a62e756b57","https://git.kernel.org/stable/c/9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99140","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-99140","identifiers":["CVE-2026-99140"]},"retained":false,"historicalAffected":[]}],"coverage":[]}