CVE-2024-35985

2024-05-2010:15:12

416baaa9-dc9f-4396-8d5f-8c081fb06d67

web.nvd.nist.gov

linux kernel

vulnerability

cve-2024-35985

sched/eevdf

reweight_eevdf()

entity_eligible()

vlag

vruntime

update_entity_lag()

nvd

6.6 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.6%

JSON

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 configurations

Vulners

Node

linuxlinux_kernelRange6.7–6.6.30

linuxlinux_kernelRange6.7.0–6.8.9

linuxlinux_kernelRange6.9.0≥

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "kernel/sched/fair.c"
    ],
    "versions": [
      {
        "version": "14204acc09f6",
        "lessThan": "470d347b14b0",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "eab03c23c2a1",
        "lessThan": "06f27e6d7bf0",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "eab03c23c2a1",
        "lessThan": "1560d1f6eb6b",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "kernel/sched/fair.c"
    ],
    "versions": [
      {
        "version": "6.7",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.7",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.30",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8.9",
        "lessThanOrEqual": "6.8.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]