CVE-2026-98076 (GCVE-0-2026-98076)
Vulnerability from cvelistv5
Published
2026-09-25 10:24
Modified
2026-10-19 09:13
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing/probes: Fix use-after-free on field name/type of events with multiple probes The fields of a probe-based dynamic event (kprobe, uprobe, eprobe and fprobe events) are created in traceprobe_define_arg_fields() by handing the probe_arg name/type strings to trace_define_field(), which only stores the pointers without copying. Those strings are owned by the trace_probe and are freed when that probe is removed. An event can have several probes attached. The field list is defined only once, by the first probe that registers the event, but it is kept alive by any surviving sibling probe. Deleting just that first probe by symbol - # primary A: fields are defined from A's args echo 'p:kprobes/ev vfs_read a1=$arg1' > kprobe_events # append B: shares A's event call echo 'p:kprobes/ev vfs_write a1=$arg1' >> kprobe_events # delete only A (matched by symbol), B survives echo '-:kprobes/ev vfs_read' >> kprobe_events frees A's args (trace_probe_cleanup() -> traceprobe_free_probe_arg()), but trace_probe_unlink() keeps the trace_probe_event because the probe list is not empty. The event call stays registered via B while its fields now reference freed memory. Any field lookup then reads it, e.g. echo 'a1 == 1' > events/kprobes/ev/filter BUG: KASAN: slab-use-after-free in strcmp+0xa7/0xb0 Call Trace: strcmp trace_find_event_field parse_pred process_preds create_filter apply_event_filter event_filter_write field->name references parg->name (kstrdup'd, freed with the probe) and, for array arguments, field->type references parg->fmt (kmalloc'd, freed with the probe) - the scalar type otherwise points at the static fmttype rodata, which is safe. Have traceprobe_define_arg_fields() duplicate the name and type strings and anchor the copies on the trace_probe_event, which embeds the event call and outlives every individual probe; trace_probe_event_free() releases them. The reproducer above triggers reliably; the field lookup and the delete both run under event_mutex, so this is a dangling reference after removal rather than a race. The issue was found by the autokbug dynamic kernel fuzzer at Tencent Yunding Lab.
References
Impacted products
Vendor Product Version
Linux Linux Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
Version: ca89bc071d5e4e981dcc52e0ca90f4500d332e42
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{
  "containers": {
    "cna": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/trace_probe.c",
            "kernel/trace/trace_probe.h"
          ],
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          "vendor": "Linux",
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          "vendor": "Linux",
          "versions": [
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              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/probes: Fix use-after-free on field name/type of events with multiple probes\n\nThe fields of a probe-based dynamic event (kprobe, uprobe, eprobe and\nfprobe events) are created in traceprobe_define_arg_fields() by handing\nthe probe_arg name/type strings to trace_define_field(), which only\nstores the pointers without copying. Those strings are owned by the\ntrace_probe and are freed when that probe is removed.\n\nAn event can have several probes attached. The field list is defined\nonly once, by the first probe that registers the event, but it is kept\nalive by any surviving sibling probe. Deleting just that first probe by\nsymbol -\n\n  # primary A: fields are defined from A\u0027s args\n  echo \u0027p:kprobes/ev vfs_read  a1=$arg1\u0027 \u003e  kprobe_events\n  # append B: shares A\u0027s event call\n  echo \u0027p:kprobes/ev vfs_write a1=$arg1\u0027 \u003e\u003e kprobe_events\n  # delete only A (matched by symbol), B survives\n  echo \u0027-:kprobes/ev vfs_read\u0027           \u003e\u003e kprobe_events\n\nfrees A\u0027s args (trace_probe_cleanup() -\u003e traceprobe_free_probe_arg()),\nbut trace_probe_unlink() keeps the trace_probe_event because the probe\nlist is not empty. The event call stays registered via B while its\nfields now reference freed memory. Any field lookup then reads it, e.g.\n\n  echo \u0027a1 == 1\u0027 \u003e events/kprobes/ev/filter\n\n  BUG: KASAN: slab-use-after-free in strcmp+0xa7/0xb0\n  Call Trace:\n   strcmp\n   trace_find_event_field\n   parse_pred\n   process_preds\n   create_filter\n   apply_event_filter\n   event_filter_write\n\nfield-\u003ename references parg-\u003ename (kstrdup\u0027d, freed with the probe) and,\nfor array arguments, field-\u003etype references parg-\u003efmt (kmalloc\u0027d, freed\nwith the probe) - the scalar type otherwise points at the static\nfmttype rodata, which is safe.\n\nHave traceprobe_define_arg_fields() duplicate the name and type strings\nand anchor the copies on the trace_probe_event, which embeds the event\ncall and outlives every individual probe; trace_probe_event_free()\nreleases them.\n\nThe reproducer above triggers reliably; the field lookup and the delete\nboth run under event_mutex, so this is a dangling reference after\nremoval rather than a race.\n\nThe issue was found by the autokbug dynamic kernel fuzzer at Tencent\nYunding Lab."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:13:25.874Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/38305e1b8b1ec27eef8f2d4e461e3b6c8624d494"
        },
        {
          "url": "https://git.kernel.org/stable/c/6d6118c17bc791594cbfd9cc4936ee21073b894a"
        },
        {
          "url": "https://git.kernel.org/stable/c/a2510fcaad92b09b34574c97e8356234c6a84a9a"
        },
        {
          "url": "https://git.kernel.org/stable/c/9379e193826f23876daccb3351fab89c87084ba3"
        },
        {
          "url": "https://git.kernel.org/stable/c/68ae584169c7a41fc9bc4677c1d368983cf44b21"
        },
        {
          "url": "https://git.kernel.org/stable/c/411c9080a776577664531b4f7d3ee53b7a747ba8"
        },
        {
          "url": "https://git.kernel.org/stable/c/178ff2e011e21fbebdf57f5d58a408fe59136d82"
        },
        {
          "url": "https://git.kernel.org/stable/c/86b7a239ec6b14a7544200ede85474c6f5526049"
        }
      ],
      "title": "tracing/probes: Fix use-after-free on field name/type of events with multiple probes",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98076",
    "datePublished": "2026-09-25T10:24:15.085Z",
    "dateReserved": "2026-09-25T10:19:56.074Z",
    "dateUpdated": "2026-10-19T09:13:25.874Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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