ghsa-qxjr-36pm-q2q2
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
Revert "libfs: fix infinite directory reads for offset dir"
The current directory offset allocator (based on mtree_alloc_cyclic) stores the next offset value to return in octx->next_offset. This mechanism typically returns values that increase monotonically over time. Eventually, though, the newly allocated offset value wraps back to a low number (say, 2) which is smaller than other already- allocated offset values.
Yu Kuai yukuai3@huawei.com reports that, after commit 64a7ce76fb90 ("libfs: fix infinite directory reads for offset dir"), if a directory's offset allocator wraps, existing entries are no longer visible via readdir/getdents because offset_readdir() stops listing entries once an entry's offset is larger than octx->next_offset. These entries vanish persistently -- they can be looked up, but will never again appear in readdir(3) output.
The reason for this is that the commit treats directory offsets as monotonically increasing integer values rather than opaque cookies, and introduces this comparison:
if (dentry2offset(dentry) >= last_index) {
On 64-bit platforms, the directory offset value upper bound is 2^63 - 1. Directory offsets will monotonically increase for millions of years without wrapping.
On 32-bit platforms, however, LONG_MAX is 2^31 - 1. The allocator can wrap after only a few weeks (at worst).
Revert commit 64a7ce76fb90 ("libfs: fix infinite directory reads for offset dir") to prepare for a fix that can work properly on 32-bit systems and might apply to recent LTS kernels where shmem employs the simple_offset mechanism.
{
"affected": [],
"aliases": [
"CVE-2024-57952"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-12T14:15:31Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nRevert \"libfs: fix infinite directory reads for offset dir\"\n\nThe current directory offset allocator (based on mtree_alloc_cyclic)\nstores the next offset value to return in octx-\u003enext_offset. This\nmechanism typically returns values that increase monotonically over\ntime. Eventually, though, the newly allocated offset value wraps\nback to a low number (say, 2) which is smaller than other already-\nallocated offset values.\n\nYu Kuai \u003cyukuai3@huawei.com\u003e reports that, after commit 64a7ce76fb90\n(\"libfs: fix infinite directory reads for offset dir\"), if a\ndirectory\u0027s offset allocator wraps, existing entries are no longer\nvisible via readdir/getdents because offset_readdir() stops listing\nentries once an entry\u0027s offset is larger than octx-\u003enext_offset.\nThese entries vanish persistently -- they can be looked up, but will\nnever again appear in readdir(3) output.\n\nThe reason for this is that the commit treats directory offsets as\nmonotonically increasing integer values rather than opaque cookies,\nand introduces this comparison:\n\n\tif (dentry2offset(dentry) \u003e= last_index) {\n\nOn 64-bit platforms, the directory offset value upper bound is\n2^63 - 1. Directory offsets will monotonically increase for millions\nof years without wrapping.\n\nOn 32-bit platforms, however, LONG_MAX is 2^31 - 1. The allocator\ncan wrap after only a few weeks (at worst).\n\nRevert commit 64a7ce76fb90 (\"libfs: fix infinite directory reads for\noffset dir\") to prepare for a fix that can work properly on 32-bit\nsystems and might apply to recent LTS kernels where shmem employs\nthe simple_offset mechanism.",
"id": "GHSA-qxjr-36pm-q2q2",
"modified": "2025-02-14T18:30:49Z",
"published": "2025-02-12T15:31:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-57952"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3f250b82040a72b0059ae00855a74d8570ad2147"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9e9e710f68bac49bd9b587823c077d06363440e0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b662d858131da9a8a14e68661656989b14dbf113"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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.