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LinuxCVE-2022-48921

HistoryAug 22, 2024 - 2:15 a.m.

CVE-2022-48921

2024-08-2202:15:08

CWE-362

Linux

web.nvd.nist.gov

linux kernel

reweight_entity

race condition

fix

cve-2022-48921

sched/fair

syzbot

gpf

null pointer dereference

CVSS3

4.7

Attack Vector

LOCAL

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

AI Score

6.5

Confidence

High

EPSS

Percentile

5.1%

JSON

In the Linux kernel, the following vulnerability has been resolved:

sched/fair: Fix fault in reweight_entity

Syzbot found a GPF in reweight_entity. This has been bisected to
commit 4ef0c5c6b5ba (“kernel/sched: Fix sched_fork() access an invalid
sched_task_group”)

There is a race between sched_post_fork() and setpriority(PRIO_PGRP)
within a thread group that causes a null-ptr-deref in
reweight_entity() in CFS. The scenario is that the main process spawns
number of new threads, which then call setpriority(PRIO_PGRP, 0, -20),
wait, and exit. For each of the new threads the copy_process() gets
invoked, which adds the new task_struct and calls sched_post_fork()
for it.

In the above scenario there is a possibility that
setpriority(PRIO_PGRP) and set_one_prio() will be called for a thread
in the group that is just being created by copy_process(), and for
which the sched_post_fork() has not been executed yet. This will
trigger a null pointer dereference in reweight_entity(), as it will
try to access the run queue pointer, which hasn’t been set.

Before the mentioned change the cfs_rq pointer for the task has been
set in sched_fork(), which is called much earlier in copy_process(),
before the new task is added to the thread_group. Now it is done in
the sched_post_fork(), which is called after that. To fix the issue
the remove the update_load param from the update_load param() function
and call reweight_task() only if the task flag doesn’t have the
TASK_NEW flag set.

Affected configurations

Nvd

Vulners

Node

linuxlinux_kernelRange5.10.80–5.10.137

linuxlinux_kernelRange5.14.19–5.15

linuxlinux_kernelRange5.15.3–5.15.27

linuxlinux_kernelRange5.16–5.16.13

linuxlinux_kernelMatch5.17rc1

linuxlinux_kernelMatch5.17rc2

linuxlinux_kernelMatch5.17rc3

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linuxlinux_kernel5.17cpe:2.3:o:linux:linux_kernel:5.17:rc1:*:*:*:*:*:*
linuxlinux_kernel5.17cpe:2.3:o:linux:linux_kernel:5.17:rc2:*:*:*:*:*:*
linuxlinux_kernel5.17cpe:2.3:o:linux:linux_kernel:5.17:rc3:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	5.17	cpe:2.3:o:linux:linux_kernel:5.17:rc1::::::
linux	linux_kernel	5.17	cpe:2.3:o:linux:linux_kernel:5.17:rc2::::::
linux	linux_kernel	5.17	cpe:2.3:o:linux:linux_kernel:5.17:rc3::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "kernel/sched/core.c"
    ],
    "versions": [
      {
        "version": "c85c6fadbef0",
        "lessThan": "8f317cd88805",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "3869eecf0504",
        "lessThan": "e0bcd6b57793",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "4ef0c5c6b5ba",
        "lessThan": "589a954daab5",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "4ef0c5c6b5ba",
        "lessThan": "13765de8148f",
        "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/core.c"
    ],
    "versions": [
      {
        "version": "5.16",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.16",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.137",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.27",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.16.13",
        "lessThanOrEqual": "5.16.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.17",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]