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CVE Record

CVE-2023-54246: rcuscale: Move rcu_scale_writer() schedule_timeout_uninterruptible() to _idle()

In the Linux kernel, the following vulnerability has been resolved: rcuscale: Move rcu_scale_writer() schedule_timeout_uninterruptible() to _idle() The rcuscale.holdoff module parameter can be used to delay the start of rcu_scale_writer() kthread. However, the hung-task timeout will trigger when the timeout specified by rcuscale.holdoff is greater than hung_task_timeout_secs: runqemu kvm nographic slirp qemuparams="-smp 4 -m 2048M" bootparams="rcuscale.shutdown=0 rcuscale.holdoff=300" [ 247.071753] INFO: task rcu_scale_write:59 blocked for more than 122 seconds. [ 247.072529] Not tainted 6.4.0-rc1-00134-gb9ed6de8d4ff #7 [ 247.073400] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 247.074331] task:rcu_scale_write state:D stack:30144 pid:59 ppid:2 flags:0x00004000 [ 247.075346] Call Trace: [ 247.075660] <TASK> [ 247.075965] __schedule+0x635/0x1280 [ 247.076448] ? __pfx___schedule+0x10/0x10 [ 247.076967] ? schedule_timeout+0x2dc/0x4d0 [ 247.077471] ? __pfx_lock_release+0x10/0x10 [ 247.078018] ? enqueue_timer+0xe2/0x220 [ 247.078522] schedule+0x84/0x120 [ 247.078957] schedule_timeout+0x2e1/0x4d0 [ 247.079447] ? __pfx_schedule_timeout+0x10/0x10 [ 247.080032] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.080591] ? __pfx_process_timeout+0x10/0x10 [ 247.081163] ? __pfx_sched_set_fifo_low+0x10/0x10 [ 247.081760] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.082287] rcu_scale_writer+0x6b1/0x7f0 [ 247.082773] ? mark_held_locks+0x29/0xa0 [ 247.083252] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.083865] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.084412] kthread+0x179/0x1c0 [ 247.084759] ? __pfx_kthread+0x10/0x10 [ 247.085098] ret_from_fork+0x2c/0x50 [ 247.085433] </TASK> This commit therefore replaces schedule_timeout_uninterruptible() with schedule_timeout_idle().

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can cause false hung-task reports when the rcuscale holdoff setting delays a writer thread longer than the kernel hung-task timeout. It appears operationally narrow and tied to a specific kernel test/scaling path, not a general remote compromise issue.

Executive priority

Treat as low urgency unless affected kernels run rcuscale testing configurations. Prioritize through normal kernel maintenance rather than emergency response.

Technical view

The rcuscale.holdoff module parameter can delay rcu_scale_writer(). When the delay exceeds hung_task_timeout_secs, schedule_timeout_uninterruptible() leaves the kthread appearing blocked. The resolved change replaces it with schedule_timeout_idle(), reflecting an intentional idle wait instead of a hung task.

Likely exposure

Exposure is most likely on affected Linux kernels where rcuscale is used with rcuscale.holdoff set higher than hung_task_timeout_secs. The provided data does not show ordinary network-facing exposure or application-level impact.

Exploitation context

The source bundle does not report active exploitation, KEV listing, exploit availability, privilege escalation, or remote attack behavior. The described trigger is a kernel boot/module parameter configuration causing hung-task warnings.

Researcher notes

Affected-version evidence is limited and unusually represented in the bundle. Validation should focus on source-level fix presence and runtime rcuscale.holdoff configuration. No CVSS, CWE, or exploitation evidence is provided.

Mitigation direction

  • Update to a Linux kernel containing the referenced stable fixes.
  • Check Linux distribution advisories for packaged kernel status.
  • Avoid rcuscale.holdoff values above hung_task_timeout_secs until patched.
  • Review whether rcuscale testing is needed on production systems.

Validation and detection

  • Check running kernel version against vendor fixed packages or referenced commits.
  • Review boot parameters for rcuscale.holdoff usage.
  • Compare rcuscale.holdoff with /proc/sys/kernel/hung_task_timeout_secs.
  • Search kernel logs for rcu_scale_write hung-task messages.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
6Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxdf37e66bfdbb57e8cae7dbf39a0c66b1b8701338, df37e66bfdbb57e8cae7dbf39a0c66b1b8701338, df37e66bfdbb57e8cae7dbf39a0c66b1b8701338, df37e66bfdbb57e8cae7dbf39a0c66b1b8701338, df37e66bfdbb57e8cae7dbf39a0c66b1b8701338unaffected
LinuxLinux4.7, 0, 5.10.197, 5.15.133, 6.1.55, 6.5.5, 6.6affected
Weakness

CWE details

No CWE listed

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