CVE-2026-93111 (GCVE-0-2026-93111)
Vulnerability from cvelistv5
Published
2026-09-17 16:11
Modified
2026-10-19 09:05
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Mark tracing_multi trampolines as ftrace managed Since tracing_multi link does not set ftrace_managed, it would fail to release the tracing_multi link when attaching tracing_multi link and then attaching fentry link. [ 3.714215] WARNING: kernel/bpf/trampoline.c:1727 at bpf_trampoline_multi_detach+0x20b/0x240, CPU#1: test_progs/97 ... [ 3.733170] bpf_tracing_multi_link_release+0x14/0x30 [ 3.733890] bpf_link_free+0x58/0x130 [ 3.734414] bpf_link_release+0x23/0x30 Fix it by setting 'ftrace_managed = true' in register_fentry_multi().
Impacted products
Vendor Product Version
Linux Linux Version: aef4dfa790b22d8052cfb78044eadbe03c876c39
Version: aef4dfa790b22d8052cfb78044eadbe03c876c39
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/trampoline.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "280145253fd38fa975cc04963ddaf74c7f415011",
              "status": "affected",
              "version": "aef4dfa790b22d8052cfb78044eadbe03c876c39",
              "versionType": "git"
            },
            {
              "lessThan": "30bdd6d1384d894931f113eb595636092d8e650c",
              "status": "affected",
              "version": "aef4dfa790b22d8052cfb78044eadbe03c876c39",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/trampoline.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Mark tracing_multi trampolines as ftrace managed\n\nSince tracing_multi link does not set ftrace_managed, it would fail to\nrelease the tracing_multi link when attaching tracing_multi link and\nthen attaching fentry link.\n\n[    3.714215] WARNING: kernel/bpf/trampoline.c:1727 at bpf_trampoline_multi_detach+0x20b/0x240, CPU#1: test_progs/97\n...\n[    3.733170]  bpf_tracing_multi_link_release+0x14/0x30\n[    3.733890]  bpf_link_free+0x58/0x130\n[    3.734414]  bpf_link_release+0x23/0x30\n\nFix it by setting \u0027ftrace_managed = true\u0027 in register_fentry_multi()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Reached only via local bpf(2): BPF_PROG_LOAD of BPF_TRACE_FENTRY_MULTI then BPF_LINK_CREATE \u2192 link_create() \u2192 bpf_tracing_multi_attach() \u2192 register_fentry_multi(), then a regular BPF_TRACE_FENTRY BPF_LINK_CREATE through bpf_tracing_prog_attach(). The trigger is that attach order, not a remote protocol message.\nAC:L - The attacker chooses the order: tracing_multi first so register_fentry_multi() never sets tr-\u003efunc.ftrace_managed, then fentry so modify_fentry() takes bpf_arch_text_poke() instead of direct_ops_mod(), then close() of the tracing_multi fd into bpf_trampoline_multi_detach(). No race or uninfluenced victim state is required.\nPR:L - bpf_prog_load() for BPF_PROG_TYPE_TRACING (fentry.multi and fentry) requires bpf_token_capable(CAP_BPF) and, via is_perfmon_prog_type(), bpf_token_capable(CAP_PERFMON). Those caps are delegable with a BPF token into a non-init user namespace, so this is Low rather than init-namespace root.\nUI:N - The attacker loads both programs, creates the tracing_multi and fentry links, and closes the tracing_multi fd themselves (bpf_link_release \u2192 bpf_tracing_multi_link_release). No other user must mount, open, or otherwise act on attacker-supplied objects.\nS:U - The use-after-free is of a kernel bpf_tramp_image that remains an ftrace direct-call target. That is in-kernel privilege escalation, not a KVM/Xen guest-to-host or IOMMU boundary cross, so scope stays Unchanged.\nC:H - modify_fentry() text-pokes the fentry site to Image B and bpf_tramp_image_put()s Image A; bpf_trampoline_multi_detach() still bpf_tramp_image_put()s Image B in bpf_trampoline_multi_attach_free() after update_ftrace_direct_del/mod fails, so a later call of the hooked function executes freed trampoline memory.\nI:H - The hooked function\u2019s live CALL/JMP still targets the trampoline image bpf_trampoline_multi_attach_free() freed after the failed ftrace update, so reclaiming that JIT page hijacks control flow at the ftrace site (arbitrary kernel write/execute).\nA:H - bpf_trampoline_multi_detach() hits WARN_ON_ONCE(update_ftrace_direct_del()) at trampoline.c:1727 when ftrace\u2019s recorded direct target no longer matches the poked site, and the subsequent jump into the freed bpf_tramp_image oopses or panics."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:05:44.850Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/280145253fd38fa975cc04963ddaf74c7f415011"
        },
        {
          "url": "https://git.kernel.org/stable/c/30bdd6d1384d894931f113eb595636092d8e650c"
        }
      ],
      "title": "bpf: Mark tracing_multi trampolines as ftrace managed",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93111",
    "datePublished": "2026-09-17T16:11:20.464Z",
    "dateReserved": "2026-09-17T16:02:15.086Z",
    "dateUpdated": "2026-10-19T09:05:44.850Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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