ghsa-qp9g-95jm-jwfj
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
sched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf()
It was possible to have pick_eevdf() return NULL, which then causes a NULL-deref. This turned out to be due to entity_eligible() returning falsely negative because of a s64 multiplcation overflow.
Specifically, reweight_eevdf() computes the vlag without considering the limit placed upon vlag as update_entity_lag() does, and then the scaling multiplication (remember that weight is 20bit fixed point) can overflow. This then leads to the new vruntime being weird which then causes the above entity_eligible() to go side-ways and claim nothing is eligible.
Thus limit the range of vlag accordingly.
All this was quite rare, but fatal when it does happen.
{
"affected": [],
"aliases": [
"CVE-2024-35985"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-20T10:15:12Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf()\n\nIt was possible to have pick_eevdf() return NULL, which then causes a\nNULL-deref. This turned out to be due to entity_eligible() returning\nfalsely negative because of a s64 multiplcation overflow.\n\nSpecifically, reweight_eevdf() computes the vlag without considering\nthe limit placed upon vlag as update_entity_lag() does, and then the\nscaling multiplication (remember that weight is 20bit fixed point) can\noverflow. This then leads to the new vruntime being weird which then\ncauses the above entity_eligible() to go side-ways and claim nothing\nis eligible.\n\nThus limit the range of vlag accordingly.\n\nAll this was quite rare, but fatal when it does happen.",
"id": "GHSA-qp9g-95jm-jwfj",
"modified": "2024-05-20T12:30:29Z",
"published": "2024-05-20T12:30:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35985"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/06f27e6d7bf0abf54488259ef36bbf0e1fccb35c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1560d1f6eb6b398bddd80c16676776c0325fe5fe"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/470d347b14b0ecffa9b39cf8f644fa2351db3efb"
}
],
"schema_version": "1.4.0",
"severity": []
}