CVE-2025-21771

MEDIUM EPSS 8.4%
Published Feb 27, 20251y ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
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Published Feb 27, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix incorrect autogroup migration detection scx_move_task() is called from sched_move_task() and tells the BPF scheduler that cgroup migration is being committed. sched_move_task() is used by both cgroup and autogroup migrations and scx_move_task() tried to filter out autogroup migrations by testing the destination cgroup and PF_EXITING but this is not enough. In fact, without explicitly tagging the thread which is doing the cgroup migration, there is no good way to tell apart scx_move_task() invocations for racing migration to the root cgroup and an autogroup migration. This led to scx_move_task() incorrectly ignoring a migration from non-root cgroup to an autogroup of the root cgroup triggering the following warning: WARNING: CPU: 7 PID: 1 at kernel/sched/ext.c:3725 scx_cgroup_can_attach+0x196/0x340 ... Call Trace: <TASK> cgroup_migrate_execute+0x5b1/0x700 cgroup_attach_task+0x296/0x400 __cgroup_procs_write+0x128/0x140 cgroup_procs_write+0x17/0x30 kernfs_fop_write_iter+0x141/0x1f0 vfs_write+0x31d/0x4a0 __x64_sys_write+0x72/0xf0 do_syscall_64+0x82/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e Fix it by adding an argument to sched_move_task() that indicates whether the moving is for a cgroup or autogroup migration. After the change, scx_move_task() is called only for cgroup migrations and renamed to scx_cgroup_move_task().

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
8.4% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Affected Products 4

VendorProductVersionRange
linuxlinux_kernel*≥6.12  –  <6.12.16
linuxlinux_kernel*≥6.13  –  <6.13.4
linuxlinux_kernel6.14any
linuxlinux_kernel6.14any

References 3

  • git.kernel.org https://git.kernel.org/stable/c/75bf2f80c046d2ec5a07455891ea0a9fb6d8b5f6
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d6f3e7d564b2309e1f17e709a70eca78d7ca2bb8
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d8b510d0ddc65d8a71e0f9a3acc9ed5f010fc514
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/75bf2f80c046d2ec5a07455891ea0a9fb6d8b5f6
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d6f3e7d564b2309e1f17e709a70eca78d7ca2bb8
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d8b510d0ddc65d8a71e0f9a3acc9ed5f010fc514
    Patch