gsd-2021-46988
Vulnerability from gsd
Modified
2024-02-28 06:03
Details
In the Linux kernel, the following vulnerability has been resolved:
userfaultfd: release page in error path to avoid BUG_ON
Consider the following sequence of events:
1. Userspace issues a UFFD ioctl, which ends up calling into
shmem_mfill_atomic_pte(). We successfully account the blocks, we
shmem_alloc_page(), but then the copy_from_user() fails. We return
-ENOENT. We don't release the page we allocated.
2. Our caller detects this error code, tries the copy_from_user() after
dropping the mmap_lock, and retries, calling back into
shmem_mfill_atomic_pte().
3. Meanwhile, let's say another process filled up the tmpfs being used.
4. So shmem_mfill_atomic_pte() fails to account blocks this time, and
immediately returns - without releasing the page.
This triggers a BUG_ON in our caller, which asserts that the page
should always be consumed, unless -ENOENT is returned.
To fix this, detect if we have such a "dangling" page when accounting
fails, and if so, release it before returning.
Aliases
{
"gsd": {
"metadata": {
"exploitCode": "unknown",
"remediation": "unknown",
"reportConfidence": "confirmed",
"type": "vulnerability"
},
"osvSchema": {
"aliases": [
"CVE-2021-46988"
],
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: release page in error path to avoid BUG_ON\n\nConsider the following sequence of events:\n\n1. Userspace issues a UFFD ioctl, which ends up calling into\n shmem_mfill_atomic_pte(). We successfully account the blocks, we\n shmem_alloc_page(), but then the copy_from_user() fails. We return\n -ENOENT. We don\u0027t release the page we allocated.\n2. Our caller detects this error code, tries the copy_from_user() after\n dropping the mmap_lock, and retries, calling back into\n shmem_mfill_atomic_pte().\n3. Meanwhile, let\u0027s say another process filled up the tmpfs being used.\n4. So shmem_mfill_atomic_pte() fails to account blocks this time, and\n immediately returns - without releasing the page.\n\nThis triggers a BUG_ON in our caller, which asserts that the page\nshould always be consumed, unless -ENOENT is returned.\n\nTo fix this, detect if we have such a \"dangling\" page when accounting\nfails, and if so, release it before returning.",
"id": "GSD-2021-46988",
"modified": "2024-02-28T06:03:57.654866Z",
"schema_version": "1.4.0"
}
},
"namespaces": {
"cve.org": {
"CVE_data_meta": {
"ASSIGNER": "cve@kernel.org",
"ID": "CVE-2021-46988",
"STATE": "PUBLIC"
},
"affects": {
"vendor": {
"vendor_data": [
{
"product": {
"product_data": [
{
"product_name": "Linux",
"version": {
"version_data": [
{
"version_affected": "\u003c",
"version_name": "cb658a453b93",
"version_value": "319116227e52"
},
{
"version_value": "not down converted",
"x_cve_json_5_version_data": {
"defaultStatus": "affected",
"versions": [
{
"status": "affected",
"version": "4.11"
},
{
"lessThan": "4.11",
"status": "unaffected",
"version": "0",
"versionType": "custom"
},
{
"lessThanOrEqual": "4.14.*",
"status": "unaffected",
"version": "4.14.233",
"versionType": "custom"
},
{
"lessThanOrEqual": "4.19.*",
"status": "unaffected",
"version": "4.19.191",
"versionType": "custom"
},
{
"lessThanOrEqual": "5.4.*",
"status": "unaffected",
"version": "5.4.120",
"versionType": "custom"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.38",
"versionType": "custom"
},
{
"lessThanOrEqual": "5.11.*",
"status": "unaffected",
"version": "5.11.22",
"versionType": "custom"
},
{
"lessThanOrEqual": "5.12.*",
"status": "unaffected",
"version": "5.12.5",
"versionType": "custom"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "5.13",
"versionType": "original_commit_for_fix"
}
]
}
}
]
}
}
]
},
"vendor_name": "Linux"
}
]
}
},
"data_format": "MITRE",
"data_type": "CVE",
"data_version": "4.0",
"description": {
"description_data": [
{
"lang": "eng",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: release page in error path to avoid BUG_ON\n\nConsider the following sequence of events:\n\n1. Userspace issues a UFFD ioctl, which ends up calling into\n shmem_mfill_atomic_pte(). We successfully account the blocks, we\n shmem_alloc_page(), but then the copy_from_user() fails. We return\n -ENOENT. We don\u0027t release the page we allocated.\n2. Our caller detects this error code, tries the copy_from_user() after\n dropping the mmap_lock, and retries, calling back into\n shmem_mfill_atomic_pte().\n3. Meanwhile, let\u0027s say another process filled up the tmpfs being used.\n4. So shmem_mfill_atomic_pte() fails to account blocks this time, and\n immediately returns - without releasing the page.\n\nThis triggers a BUG_ON in our caller, which asserts that the page\nshould always be consumed, unless -ENOENT is returned.\n\nTo fix this, detect if we have such a \"dangling\" page when accounting\nfails, and if so, release it before returning."
}
]
},
"generator": {
"engine": "bippy-c298863b1525"
},
"problemtype": {
"problemtype_data": [
{
"description": [
{
"lang": "eng",
"value": "n/a"
}
]
}
]
},
"references": {
"reference_data": [
{
"name": "https://git.kernel.org/stable/c/319116227e52d49eee671f0aa278bac89b3c1b69",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/319116227e52d49eee671f0aa278bac89b3c1b69"
},
{
"name": "https://git.kernel.org/stable/c/07c9b834c97d0fa3402fb7f3f3b32df370a6ff1f",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/07c9b834c97d0fa3402fb7f3f3b32df370a6ff1f"
},
{
"name": "https://git.kernel.org/stable/c/b3f1731c6d7fbc1ebe3ed8eff6d6bec56d76ff43",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/b3f1731c6d7fbc1ebe3ed8eff6d6bec56d76ff43"
},
{
"name": "https://git.kernel.org/stable/c/140cfd9980124aecb6c03ef2e69c72d0548744de",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/140cfd9980124aecb6c03ef2e69c72d0548744de"
},
{
"name": "https://git.kernel.org/stable/c/ad53127973034c63b5348715a1043d0e80ceb330",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/ad53127973034c63b5348715a1043d0e80ceb330"
},
{
"name": "https://git.kernel.org/stable/c/2d59a0ed8b26b8f3638d8afc31f839e27759f1f6",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/2d59a0ed8b26b8f3638d8afc31f839e27759f1f6"
},
{
"name": "https://git.kernel.org/stable/c/7ed9d238c7dbb1fdb63ad96a6184985151b0171c",
"refsource": "MISC",
"url": "https://git.kernel.org/stable/c/7ed9d238c7dbb1fdb63ad96a6184985151b0171c"
}
]
}
},
"nvd.nist.gov": {
"cve": {
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: release page in error path to avoid BUG_ON\n\nConsider the following sequence of events:\n\n1. Userspace issues a UFFD ioctl, which ends up calling into\n shmem_mfill_atomic_pte(). We successfully account the blocks, we\n shmem_alloc_page(), but then the copy_from_user() fails. We return\n -ENOENT. We don\u0027t release the page we allocated.\n2. Our caller detects this error code, tries the copy_from_user() after\n dropping the mmap_lock, and retries, calling back into\n shmem_mfill_atomic_pte().\n3. Meanwhile, let\u0027s say another process filled up the tmpfs being used.\n4. So shmem_mfill_atomic_pte() fails to account blocks this time, and\n immediately returns - without releasing the page.\n\nThis triggers a BUG_ON in our caller, which asserts that the page\nshould always be consumed, unless -ENOENT is returned.\n\nTo fix this, detect if we have such a \"dangling\" page when accounting\nfails, and if so, release it before returning."
}
],
"id": "CVE-2021-46988",
"lastModified": "2024-02-28T14:06:45.783",
"metrics": {},
"published": "2024-02-28T09:15:37.640",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/07c9b834c97d0fa3402fb7f3f3b32df370a6ff1f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/140cfd9980124aecb6c03ef2e69c72d0548744de"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2d59a0ed8b26b8f3638d8afc31f839e27759f1f6"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/319116227e52d49eee671f0aa278bac89b3c1b69"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7ed9d238c7dbb1fdb63ad96a6184985151b0171c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ad53127973034c63b5348715a1043d0e80ceb330"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b3f1731c6d7fbc1ebe3ed8eff6d6bec56d76ff43"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
}
}
}
Loading…
Loading…
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.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- 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.
Loading…
Loading…