fkie_cve-2024-49861
Vulnerability from fkie_nvd
Published
2024-10-21 13:15
Modified
2024-12-14 21:15
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix helper writes to read-only maps
Lonial found an issue that despite user- and BPF-side frozen BPF map
(like in case of .rodata), it was still possible to write into it from
a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT}
as arguments.
In check_func_arg() when the argument is as mentioned, the meta->raw_mode
is never set. Later, check_helper_mem_access(), under the case of
PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the
subsequent call to check_map_access_type() and given the BPF map is
read-only it succeeds.
The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT
when results are written into them as opposed to read out of them. The
latter indicates that it's okay to pass a pointer to uninitialized memory
as the memory is written to anyway.
However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM
just with additional alignment requirement. So it is better to just get
rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the
fixed size memory types. For this, add MEM_ALIGNED to additionally ensure
alignment given these helpers write directly into the args via *<ptr> = val.
The .arg*_size has been initialized reflecting the actual sizeof(*<ptr>).
MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated
argument types, since in !MEM_FIXED_SIZE cases the verifier does not know
the buffer size a priori and therefore cannot blindly write *<ptr> = val.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * |
{
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix helper writes to read-only maps\n\nLonial found an issue that despite user- and BPF-side frozen BPF map\n(like in case of .rodata), it was still possible to write into it from\na BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT}\nas arguments.\n\nIn check_func_arg() when the argument is as mentioned, the meta-\u003eraw_mode\nis never set. Later, check_helper_mem_access(), under the case of\nPTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the\nsubsequent call to check_map_access_type() and given the BPF map is\nread-only it succeeds.\n\nThe helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT\nwhen results are written into them as opposed to read out of them. The\nlatter indicates that it\u0027s okay to pass a pointer to uninitialized memory\nas the memory is written to anyway.\n\nHowever, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM\njust with additional alignment requirement. So it is better to just get\nrid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the\nfixed size memory types. For this, add MEM_ALIGNED to additionally ensure\nalignment given these helpers write directly into the args via *\u003cptr\u003e = val.\nThe .arg*_size has been initialized reflecting the actual sizeof(*\u003cptr\u003e).\n\nMEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated\nargument types, since in !MEM_FIXED_SIZE cases the verifier does not know\nthe buffer size a priori and therefore cannot blindly write *\u003cptr\u003e = val."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Arregla las escrituras del ayudante en mapas de solo lectura Lonial encontr\u00f3 un problema que a pesar del mapa BPF congelado del lado del usuario y del BPF (como en el caso de .rodata), a\u00fan era posible escribir en \u00e9l desde el lado del programa BPF a trav\u00e9s de ayudantes espec\u00edficos que tienen ARG_PTR_TO_{LONG,INT} como argumentos. En check_func_arg() cuando el argumento es como se menciona, el meta-\u0026gt;raw_mode nunca se establece. M\u00e1s tarde, check_helper_mem_access(), bajo el caso de PTR_TO_MAP_VALUE como tipo base de registro, asume BPF_READ para la llamada posterior a check_map_access_type() y dado que el mapa BPF es de solo lectura, tiene \u00e9xito. Los ayudantes realmente necesitan ser anotados como ARG_PTR_TO_{LONG,INT} | MEM_UNINIT cuando los resultados se escriben en ellos en lugar de leerse de ellos. Este \u00faltimo indica que est\u00e1 bien pasar un puntero a la memoria no inicializada, ya que la memoria se escribe de todos modos. Sin embargo, ARG_PTR_TO_{LONG,INT} es un caso especial de ARG_PTR_TO_FIXED_SIZE_MEM solo que con un requisito de alineaci\u00f3n adicional. Por lo tanto, es mejor deshacerse de los casos especiales ARG_PTR_TO_{LONG,INT} por completo y reutilizar los tipos de memoria de tama\u00f1o fijo. Para esto, agregue MEM_ALIGNED para garantizar adicionalmente la alineaci\u00f3n dado que estos ayudantes escriben directamente en los argumentos a trav\u00e9s de * = val. El .arg*_size se ha inicializado reflejando el tama\u00f1o real de (*). MEM_ALIGNED solo se puede usar en combinaci\u00f3n con los tipos de argumentos anotados MEM_FIXED_SIZE, ya que en los casos !MEM_FIXED_SIZE el verificador no conoce el tama\u00f1o del b\u00fafer a priori y, por lo tanto, no puede escribir ciegamente * = val."
}
],
"id": "CVE-2024-49861",
"lastModified": "2024-12-14T21:15:26.447",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.1,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.2,
"source": "nvd@nist.gov",
"type": "Primary"
}
]
},
"published": "2024-10-21T13:15:06.800",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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"url": "https://git.kernel.org/stable/c/1e75d25133158b525e0456876e9bcfd6b2993fd5"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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{
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},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"url": "https://git.kernel.org/stable/c/a2c8dc7e21803257e762b0bf067fd13e9c995da0"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Modified",
"weaknesses": [
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"description": [
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"lang": "en",
"value": "NVD-CWE-noinfo"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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