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CVE-2024-47794 (GCVE-0-2024-47794)

Vulnerability from cvelistv5 – Published: 2025-01-11 12:25 – Updated: 2026-08-05 11:39
VLAI
Title
bpf: Prevent tailcall infinite loop caused by freplace
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Prevent tailcall infinite loop caused by freplace There is a potential infinite loop issue that can occur when using a combination of tail calls and freplace. In an upcoming selftest, the attach target for entry_freplace of tailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in entry_freplace leads to entry_tc. This results in an infinite loop: entry_tc -> subprog_tc -> entry_freplace --tailcall-> entry_tc. The problem arises because the tail_call_cnt in entry_freplace resets to zero each time entry_freplace is executed, causing the tail call mechanism to never terminate, eventually leading to a kernel panic. To fix this issue, the solution is twofold: 1. Prevent updating a program extended by an freplace program to a prog_array map. 2. Prevent extending a program that is already part of a prog_array map with an freplace program. This ensures that: * If a program or its subprogram has been extended by an freplace program, it can no longer be updated to a prog_array map. * If a program has been added to a prog_array map, neither it nor its subprograms can be extended by an freplace program. Moreover, an extension program should not be tailcalled. As such, return -EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a prog_array map. Additionally, fix a minor code style issue by replacing eight spaces with a tab for proper formatting.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: be8704ff07d2374bcc5c675526f95e70c6459683 , < 987aa730bad3e1ef66d9f30182294daa78f6387d (git)
Affected: be8704ff07d2374bcc5c675526f95e70c6459683 , < d6083f040d5d8f8d748462c77e90547097df936e (git)
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Linux Linux Affected: 5.6
Unaffected: 0 , < 5.6 (semver)
Unaffected: 6.12.5 , ≤ 6.12.* (semver)
Unaffected: 6.13 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/bpf.h",
            "kernel/bpf/arraymap.c",
            "kernel/bpf/core.c",
            "kernel/bpf/syscall.c",
            "kernel/bpf/trampoline.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "be8704ff07d2374bcc5c675526f95e70c6459683",
              "versionType": "git"
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            {
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          "versions": [
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              "version": "5.6"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.12.5",
              "versionType": "semver"
            },
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              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.5",
                  "versionStartIncluding": "5.6",
                  "vulnerable": true
                },
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13",
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Prevent tailcall infinite loop caused by freplace\n\nThere is a potential infinite loop issue that can occur when using a\ncombination of tail calls and freplace.\n\nIn an upcoming selftest, the attach target for entry_freplace of\ntailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in\nentry_freplace leads to entry_tc. This results in an infinite loop:\n\nentry_tc -\u003e subprog_tc -\u003e entry_freplace --tailcall-\u003e entry_tc.\n\nThe problem arises because the tail_call_cnt in entry_freplace resets to\nzero each time entry_freplace is executed, causing the tail call mechanism\nto never terminate, eventually leading to a kernel panic.\n\nTo fix this issue, the solution is twofold:\n\n1. Prevent updating a program extended by an freplace program to a\n   prog_array map.\n2. Prevent extending a program that is already part of a prog_array map\n   with an freplace program.\n\nThis ensures that:\n\n* If a program or its subprogram has been extended by an freplace program,\n  it can no longer be updated to a prog_array map.\n* If a program has been added to a prog_array map, neither it nor its\n  subprograms can be extended by an freplace program.\n\nMoreover, an extension program should not be tailcalled. As such, return\n-EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a\nprog_array map.\n\nAdditionally, fix a minor code style issue by replacing eight spaces with a\ntab for proper formatting."
        }
      ],
      "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 - The entire attack is built and triggered through the local `bpf(2)` syscall \u2014 two `BPF_PROG_LOAD` calls, a `BPF_LINK_CREATE` freplace attach, a `PROG_ARRAY` map update, and `BPF_PROG_TEST_RUN`. No network peer or remote input is involved, and no netdev attachment is required.\nAC:L - The attacker constructs every component of the loop (target prog, its bpf2bpf subprog, the freplace extension, and the prog_array entry) and fires it deterministically; there is no race, no memory-layout dependency, and no state outside the attacker\u0027s control. Every invocation reproduces the runaway tail-call chain.\nPR:L - Loading `BPF_PROG_TYPE_EXT` goes through `bpf_token_capable()` for CAP_BPF/CAP_NET_ADMIN/CAP_PERFMON, which grants only `ns_capable()`-level checks when a BPF token is delegated to a user namespace via bpffs `delegate_cmds`/`delegate_progs` \u2014 so a low-privileged container process with a delegated token can reach it, and no real init-namespace root is strictly needed.\nUI:N - The attacker loads, attaches, and executes the programs entirely on its own via `BPF_PROG_TEST_RUN` or by attaching the classifier and sending itself a packet. No victim action of any kind is required.\nS:U - The corruption and the crash both occur in the kernel\u0027s own stack within the same security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The unbounded recursion is an out-of-bounds write past the kernel stack limit with attacker-chosen BPF stack contents; on builds without CONFIG_VMAP_STACK (e.g. KASAN_GENERIC configs, where `arch/Kconfig` disables it) the overflow spills into adjacent kernel memory, yielding a corruption primitive usable for disclosing kernel data.\nI:H - Same stack overflow gives an unbounded, attacker-controlled out-of-bounds write past the stack guard limit, which on non-VMAP_STACK configurations overwrites adjacent kernel structures and is leverageable for control-flow hijack; per guidance any OOB write scores High.\nA:H - The commit states the tail-call mechanism \"never terminate[s], eventually leading to a kernel panic\" \u2014 the stack grows every cycle until it hits the guard page, producing an immediate double-fault panic (or silent corruption) within microseconds, and it can be re-triggered on every packet if the classifier is attached to a live interface."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:39:59.232Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/987aa730bad3e1ef66d9f30182294daa78f6387d"
        },
        {
          "url": "https://git.kernel.org/stable/c/d6083f040d5d8f8d748462c77e90547097df936e"
        }
      ],
      "title": "bpf: Prevent tailcall infinite loop caused by freplace",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2024-47794",
    "datePublished": "2025-01-11T12:25:14.419Z",
    "dateReserved": "2025-01-09T09:49:29.737Z",
    "dateUpdated": "2026-08-05T11:39:59.232Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2024-47794",
      "date": "2026-09-16",
      "epss": "0.00204",
      "percentile": "0.10609"
    },
    "fkie_nvd": {
      "descriptions": "[{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbpf: Prevent tailcall infinite loop caused by freplace\\n\\nThere is a potential infinite loop issue that can occur when using a\\ncombination of tail calls and freplace.\\n\\nIn an upcoming selftest, the attach target for entry_freplace of\\ntailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in\\nentry_freplace leads to entry_tc. This results in an infinite loop:\\n\\nentry_tc -\u003e subprog_tc -\u003e entry_freplace --tailcall-\u003e entry_tc.\\n\\nThe problem arises because the tail_call_cnt in entry_freplace resets to\\nzero each time entry_freplace is executed, causing the tail call mechanism\\nto never terminate, eventually leading to a kernel panic.\\n\\nTo fix this issue, the solution is twofold:\\n\\n1. Prevent updating a program extended by an freplace program to a\\n   prog_array map.\\n2. Prevent extending a program that is already part of a prog_array map\\n   with an freplace program.\\n\\nThis ensures that:\\n\\n* If a program or its subprogram has been extended by an freplace program,\\n  it can no longer be updated to a prog_array map.\\n* If a program has been added to a prog_array map, neither it nor its\\n  subprograms can be extended by an freplace program.\\n\\nMoreover, an extension program should not be tailcalled. As such, return\\n-EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a\\nprog_array map.\\n\\nAdditionally, fix a minor code style issue by replacing eight spaces with a\\ntab for proper formatting.\"}]",
      "id": "CVE-2024-47794",
      "lastModified": "2025-01-11T13:15:22.390",
      "published": "2025-01-11T13:15:22.390",
      "references": "[{\"url\": \"https://git.kernel.org/stable/c/987aa730bad3e1ef66d9f30182294daa78f6387d\", \"source\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}, {\"url\": \"https://git.kernel.org/stable/c/d6083f040d5d8f8d748462c77e90547097df936e\", \"source\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]",
      "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "vulnStatus": "Received"
    },
    "microsoft_vex": {
      "current_release_date": "2026-06-28T01:55:52.000Z",
      "cve": "CVE-2024-47794",
      "id": "msrc_CVE-2024-47794",
      "initial_release_date": "2025-01-02T00:00:00.000Z",
      "product_status:known_affected": "3",
      "product_status:under_investigation": "16",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "bpf: Prevent tailcall infinite loop caused by freplace",
      "url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2024-47794.json",
      "version": "14"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2024-47794\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-01-11T13:15:22.390\",\"lastModified\":\"2026-08-04T11:20:49.140\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbpf: Prevent tailcall infinite loop caused by freplace\\n\\nThere is a potential infinite loop issue that can occur when using a\\ncombination of tail calls and freplace.\\n\\nIn an upcoming selftest, the attach target for entry_freplace of\\ntailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in\\nentry_freplace leads to entry_tc. This results in an infinite loop:\\n\\nentry_tc -\u003e subprog_tc -\u003e entry_freplace --tailcall-\u003e entry_tc.\\n\\nThe problem arises because the tail_call_cnt in entry_freplace resets to\\nzero each time entry_freplace is executed, causing the tail call mechanism\\nto never terminate, eventually leading to a kernel panic.\\n\\nTo fix this issue, the solution is twofold:\\n\\n1. Prevent updating a program extended by an freplace program to a\\n   prog_array map.\\n2. Prevent extending a program that is already part of a prog_array map\\n   with an freplace program.\\n\\nThis ensures that:\\n\\n* If a program or its subprogram has been extended by an freplace program,\\n  it can no longer be updated to a prog_array map.\\n* If a program has been added to a prog_array map, neither it nor its\\n  subprograms can be extended by an freplace program.\\n\\nMoreover, an extension program should not be tailcalled. As such, return\\n-EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a\\nprog_array map.\\n\\nAdditionally, fix a minor code style issue by replacing eight spaces with a\\ntab for proper formatting.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Evitar bucle infinito de tailcall causado por freplace Existe un posible problema de bucle infinito que puede ocurrir al usar una combinaci\u00f3n de llamadas de cola y freplace. En una pr\u00f3xima autoprueba, el objetivo de conexi\u00f3n para entry_freplace de tailcall_freplace.c es subprog_tc de tc_bpf2bpf.c, mientras que la llamada de cola en entry_freplace conduce a entry_tc. Esto da como resultado un bucle infinito: entry_tc -\u0026gt; subprog_tc -\u0026gt; entry_freplace --tailcall-\u0026gt; entry_tc. El problema surge porque tail_call_cnt en entry_freplace se restablece a cero cada vez que se ejecuta entry_freplace, lo que hace que el mecanismo de llamada de cola nunca finalice, lo que finalmente conduce a un p\u00e1nico del kernel. Para solucionar este problema, la soluci\u00f3n es doble: 1. Evitar actualizar un programa extendido por un programa freplace a un mapa prog_array. 2. Evite extender un programa que ya es parte de un mapa prog_array con un programa freplace. Esto garantiza que: * Si un programa o su subprograma ha sido extendido por un programa freplace, ya no puede actualizarse a un mapa prog_array. * Si un programa ha sido agregado a un mapa prog_array, ni \u00e9l ni sus subprogramas pueden ser extendidos por un programa freplace. Adem\u00e1s, un programa de extensi\u00f3n no debe ser llamado al final. Como tal, devuelva -EINVAL si el programa tiene un tipo de BPF_PROG_TYPE_EXT al agregarlo a un mapa prog_array. Adem\u00e1s, solucione un problema menor de estilo de c\u00f3digo reemplazando ocho espacios con una tabulaci\u00f3n para un formato adecuado.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"include/linux/bpf.h\",\"kernel/bpf/arraymap.c\",\"kernel/bpf/core.c\",\"kernel/bpf/syscall.c\",\"kernel/bpf/trampoline.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"be8704ff07d2374bcc5c675526f95e70c6459683\",\"lessThan\":\"987aa730bad3e1ef66d9f30182294daa78f6387d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"be8704ff07d2374bcc5c675526f95e70c6459683\",\"lessThan\":\"d6083f040d5d8f8d748462c77e90547097df936e\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"include/linux/bpf.h\",\"kernel/bpf/arraymap.c\",\"kernel/bpf/core.c\",\"kernel/bpf/syscall.c\",\"kernel/bpf/trampoline.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.6\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.6\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.5\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.13\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-835\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.6\",\"versionEndExcluding\":\"6.12.5\",\"matchCriteriaId\":\"83E30040-8849-4588-B81C-AE479356574C\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/987aa730bad3e1ef66d9f30182294daa78f6387d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/d6083f040d5d8f8d748462c77e90547097df936e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-08-04T22:41:08+00:00",
      "cve": "CVE-2024-47794",
      "id": "CVE-2024-47794",
      "initial_release_date": "2024-01-01T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Prevent tailcall infinite loop caused by freplace",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2024/cve-2024-47794.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-01T13:59:02Z",
      "cve": "CVE-2024-47794",
      "id": "CVE-2024-47794",
      "initial_release_date": "2025-01-12T00:18:06Z",
      "product_status:known_affected": "583",
      "product_status:known_not_affected": "215",
      "product_status:recommended": "384",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2024-47794",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2024-47794.json",
      "version": "56"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


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