CVE-2022-48921

MEDIUM EPSS 6.4%
Published Aug 22, 20241y ago · Modified Jun 17, 20261w ago
4.7 CVSS 3.1
Medium
Find Similar
Published Aug 22, 2024 1y ago
Last Modified Jun 17, 2026 1w ago

Description

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.

CVSS Details

Base Score
4.7
Exploitability
1.0
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity High
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
6.4% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-362

Affected Products 7

VendorProductVersionRange
linuxlinux_kernel*≥5.10.80  –  <5.10.137
linuxlinux_kernel*≥5.14.19  –  <5.15
linuxlinux_kernel*≥5.15.3  –  <5.15.27
linuxlinux_kernel*≥5.16  –  <5.16.13
linuxlinux_kernel5.17any
linuxlinux_kernel5.17any
linuxlinux_kernel5.17any

References 4

  • git.kernel.org https://git.kernel.org/stable/c/13765de8148f71fa795e0a6607de37c49ea5915a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/589a954daab5e18399860b6c8ffaeaf79844eb20
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8f317cd888059c59e2fa924bf4b0957cfa53f78e
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e0bcd6b5779352aed88f2e538a82a39f1a7715bb
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/13765de8148f71fa795e0a6607de37c49ea5915a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/589a954daab5e18399860b6c8ffaeaf79844eb20
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8f317cd888059c59e2fa924bf4b0957cfa53f78e
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e0bcd6b5779352aed88f2e538a82a39f1a7715bb
    Patch