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FKIE_CVE-2026-89984

Vulnerability from fkie_nvd - Published: 2026-09-16 11:17 - Updated: 2026-09-16 11:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel: Fix kernel address leakages in LBR stack Before Arch LBR gained CPL filtering support, a user-only branch stack could still contain kernel addresses. As a result, kernel branch records may be exposed to user space even when PERF_SAMPLE_BRANCH_USER is requested. For example, on Intel Tiger Lake, the following command can still report SYSRET/ERET entries with kernel-space from addresses: $ ./perf record -e cycles:p -o - --branch-filter any,save_type,u -- \ ./perf bench syscall basic --loop 1000 | \ ./perf script -i - --fields brstack|tr ' ' '\n'| \ grep -E '0x[89a-f][0-9a-f]{15}' Total time: 0.000 [sec] 0.219000 usecs/op 4,566,210 ops/sec [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.551 MB - ] 0xffffffff93c001c8/0x7f12a2b1d647/P/-/-/16959/SYSRET/- 0xffffffff93c001c8/0x7f12a2b1d5c2/P/-/-/17535/SYSRET/- 0xffffffff93c01928/0x7f12a2861000/P/-/-/6719/ERET/- 0xffffffff93c01928/0x7f12a297a000/P/-/-/8575/ERET/- The problem is that intel_pmu_lbr_filter() does not fully validate the privilege level of sampled entries. It filters some mismatches based on the branch type and the to address, but it does not reject entries whose from address violates the requested branch privilege filter. Fix this by extending software filtering to validate both from and to addresses against br_sel. Any LBR entry contains kernel address does not match the requested user filter is dropped. This prevents kernel addresses from appearing in user-only branch stacks.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3c492c8eba02698ca893a9a13388d2adf6dfb839
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/68c4b780b266a435261a1e029bede5ee3c2735cc
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6ac26161db27f7fb9d9e89ae240dbe52795496cc
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b589147f54adc62e4172e4acf079ad5fb7b3687f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/be0628a101ac05b085aaa4f650d48bd3915e80fa
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ca19a175e89b7de604fab736436cbab74030b47a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e2b0575900ff72aa82748af96e7bd564ade5157a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f3705db4e6378cc1b91a38ce0fe2f879055e23ca
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/events/intel/lbr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f3705db4e6378cc1b91a38ce0fe2f879055e23ca",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            },
            {
              "lessThan": "b589147f54adc62e4172e4acf079ad5fb7b3687f",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            },
            {
              "lessThan": "be0628a101ac05b085aaa4f650d48bd3915e80fa",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            },
            {
              "lessThan": "ca19a175e89b7de604fab736436cbab74030b47a",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            },
            {
              "lessThan": "6ac26161db27f7fb9d9e89ae240dbe52795496cc",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            },
            {
              "lessThan": "3c492c8eba02698ca893a9a13388d2adf6dfb839",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            },
            {
              "lessThan": "68c4b780b266a435261a1e029bede5ee3c2735cc",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            },
            {
              "lessThan": "e2b0575900ff72aa82748af96e7bd564ade5157a",
              "status": "affected",
              "version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/events/intel/lbr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.9"
            },
            {
              "lessThan": "5.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel: Fix kernel address leakages in LBR stack\n\nBefore Arch LBR gained CPL filtering support, a user-only branch stack\ncould still contain kernel addresses. As a result, kernel branch records\nmay be exposed to user space even when PERF_SAMPLE_BRANCH_USER is\nrequested.\n\nFor example, on Intel Tiger Lake, the following command can still report\nSYSRET/ERET entries with kernel-space from addresses:\n\n$ ./perf record -e cycles:p -o - --branch-filter any,save_type,u -- \\\n \t./perf bench syscall basic --loop 1000 | \\\n\t./perf script -i - --fields brstack|tr \u0027 \u0027 \u0027\\n\u0027| \\\n\tgrep -E \u00270x[89a-f][0-9a-f]{15}\u0027\n\n    Total time: 0.000 [sec]\n\n      0.219000 usecs/op\n     4,566,210 ops/sec\n[ perf record: Woken up 1 times to write data ]\n[ perf record: Captured and wrote 0.551 MB - ]\n0xffffffff93c001c8/0x7f12a2b1d647/P/-/-/16959/SYSRET/-\n0xffffffff93c001c8/0x7f12a2b1d5c2/P/-/-/17535/SYSRET/-\n0xffffffff93c01928/0x7f12a2861000/P/-/-/6719/ERET/-\n0xffffffff93c01928/0x7f12a297a000/P/-/-/8575/ERET/-\n\nThe problem is that intel_pmu_lbr_filter() does not fully validate the\nprivilege level of sampled entries. It filters some mismatches based on\nthe branch type and the to address, but it does not reject entries whose\nfrom address violates the requested branch privilege filter.\n\nFix this by extending software filtering to validate both from and to\naddresses against br_sel. Any LBR entry contains kernel address does not\nmatch the requested user filter is dropped. This prevents kernel\naddresses from appearing in user-only branch stacks."
    }
  ],
  "id": "CVE-2026-89984",
  "lastModified": "2026-09-16T11:17:09.403",
  "metrics": {},
  "published": "2026-09-16T11:17:09.403",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3c492c8eba02698ca893a9a13388d2adf6dfb839"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/68c4b780b266a435261a1e029bede5ee3c2735cc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6ac26161db27f7fb9d9e89ae240dbe52795496cc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b589147f54adc62e4172e4acf079ad5fb7b3687f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/be0628a101ac05b085aaa4f650d48bd3915e80fa"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ca19a175e89b7de604fab736436cbab74030b47a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e2b0575900ff72aa82748af96e7bd564ade5157a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f3705db4e6378cc1b91a38ce0fe2f879055e23ca"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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