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CVE Record

CVE-2023-53671: srcu: Delegate work to the boot cpu if using SRCU_SIZE_SMALL

In the Linux kernel, the following vulnerability has been resolved: srcu: Delegate work to the boot cpu if using SRCU_SIZE_SMALL Commit 994f706872e6 ("srcu: Make Tree SRCU able to operate without snp_node array") assumes that cpu 0 is always online. However, there really are situations when some other CPU is the boot CPU, for example, when booting a kdump kernel with the maxcpus=1 boot parameter. On PowerPC, the kdump kernel can hang as follows: ... [ 1.740036] systemd[1]: Hostname set to <xyz.com> [ 243.686240] INFO: task systemd:1 blocked for more than 122 seconds. [ 243.686264] Not tainted 6.1.0-rc1 #1 [ 243.686272] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 243.686281] task:systemd state:D stack:0 pid:1 ppid:0 flags:0x00042000 [ 243.686296] Call Trace: [ 243.686301] [c000000016657640] [c000000016657670] 0xc000000016657670 (unreliable) [ 243.686317] [c000000016657830] [c00000001001dec0] __switch_to+0x130/0x220 [ 243.686333] [c000000016657890] [c000000010f607b8] __schedule+0x1f8/0x580 [ 243.686347] [c000000016657940] [c000000010f60bb4] schedule+0x74/0x140 [ 243.686361] [c0000000166579b0] [c000000010f699b8] schedule_timeout+0x168/0x1c0 [ 243.686374] [c000000016657a80] [c000000010f61de8] __wait_for_common+0x148/0x360 [ 243.686387] [c000000016657b20] [c000000010176bb0] __flush_work.isra.0+0x1c0/0x3d0 [ 243.686401] [c000000016657bb0] [c0000000105f2768] fsnotify_wait_marks_destroyed+0x28/0x40 [ 243.686415] [c000000016657bd0] [c0000000105f21b8] fsnotify_destroy_group+0x68/0x160 [ 243.686428] [c000000016657c40] [c0000000105f6500] inotify_release+0x30/0xa0 [ 243.686440] [c000000016657cb0] [c0000000105751a8] __fput+0xc8/0x350 [ 243.686452] [c000000016657d00] [c00000001017d524] task_work_run+0xe4/0x170 [ 243.686464] [c000000016657d50] [c000000010020e94] do_notify_resume+0x134/0x140 [ 243.686478] [c000000016657d80] [c00000001002eb18] interrupt_exit_user_prepare_main+0x198/0x270 [ 243.686493] [c000000016657de0] [c00000001002ec60] syscall_exit_prepare+0x70/0x180 [ 243.686505] [c000000016657e10] [c00000001000bf7c] system_call_vectored_common+0xfc/0x280 [ 243.686520] --- interrupt: 3000 at 0x7fffa47d5ba4 [ 243.686528] NIP: 00007fffa47d5ba4 LR: 0000000000000000 CTR: 0000000000000000 [ 243.686538] REGS: c000000016657e80 TRAP: 3000 Not tainted (6.1.0-rc1) [ 243.686548] MSR: 800000000000d033 <SF,EE,PR,ME,IR,DR,RI,LE> CR: 42044440 XER: 00000000 [ 243.686572] IRQMASK: 0 [ 243.686572] GPR00: 0000000000000006 00007ffffa606710 00007fffa48e7200 0000000000000000 [ 243.686572] GPR04: 0000000000000002 000000000000000a 0000000000000000 0000000000000001 [ 243.686572] GPR08: 000001000c172dd0 0000000000000000 0000000000000000 0000000000000000 [ 243.686572] GPR12: 0000000000000000 00007fffa4ff4bc0 0000000000000000 0000000000000000 [ 243.686572] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 243.686572] GPR20: 0000000132dfdc50 000000000000000e 0000000000189375 0000000000000000 [ 243.686572] GPR24: 00007ffffa606ae0 0000000000000005 000001000c185490 000001000c172570 [ 243.686572] GPR28: 000001000c172990 000001000c184850 000001000c172e00 00007fffa4fedd98 [ 243.686683] NIP [00007fffa47d5ba4] 0x7fffa47d5ba4 [ 243.686691] LR [0000000000000000] 0x0 [ 243.686698] --- interrupt: 3000 [ 243.686708] INFO: task kworker/u16:1:24 blocked for more than 122 seconds. [ 243.686717] Not tainted 6.1.0-rc1 #1 [ 243.686724] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 243.686733] task:kworker/u16:1 state:D stack:0 pid:24 ppid:2 flags:0x00000800 [ 243.686747] Workqueue: events_unbound fsnotify_mark_destroy_workfn [ 243.686758] Call Trace: [ 243.686762] [c0000000166736e0] [c00000004fd91000] 0xc00000004fd91000 (unreliable) [ 243.686775] [c0000000166738d0] [c00000001001dec0] __switch_to+0x130/0x220 [ 243.686788] [c000000016673930] [c000000010f607b8] __schedule+0x1f8/0x ---truncated---

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel reliability issue where a crash-recovery kernel can hang during boot in specific CPU configurations. The source describes PowerPC kdump with maxcpus=1 as an observed failure case. It is not presented as data theft or remote code execution.

Executive priority

Treat this as a resilience and recovery-risk issue. It is most urgent where kdump is part of production incident response, because failure may reduce visibility after a crash.

Technical view

The SRCU change from commit 994f706872e6 assumed CPU 0 was online. In configurations where another CPU is the boot CPU, SRCU work could be delegated incorrectly, causing blocked workqueues and hung tasks during kdump kernel boot.

Likely exposure

Exposure appears concentrated in Linux systems carrying the affected SRCU change, especially PowerPC crash-dump environments using kdump with maxcpus=1 or non-CPU-0 boot scenarios. Confirm exact exposure through kernel version, vendor backports, and the referenced stable fixes.

Exploitation context

The bundle does not cite active exploitation, public exploit activity, or CISA KEV listing. The described impact is a kernel hang during a specialized boot/recovery path, not an attacker workflow.

Researcher notes

Evidence is limited to the CVE description and stable kernel references. No CVSS, CWE, exploit status, or detailed affected distro matrix is provided. Avoid assuming remote triggerability or broad impact beyond affected kernel configurations.

Mitigation direction

  • Check whether your kernel includes the referenced stable commits or vendor backports.
  • Prioritize systems that rely on kdump for incident response or crash diagnostics.
  • Review Linux distribution advisories for package-specific fixed kernel versions.
  • Test crash-dump boot paths after applying kernel updates.

Validation and detection

  • Inventory Linux kernel versions and compare against vendor advisories and stable references.
  • Identify PowerPC systems using kdump with maxcpus=1 or unusual boot CPU behavior.
  • Review boot logs for hung tasks involving SRCU, workqueues, fsnotify, or systemd startup.
  • Confirm crash-dump collection still completes after remediation.
Prepared
Confidence
medium
Sources
5

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
4Source links

Vulnerability timeline

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

  1. CVE reservedCVE Program

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  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
LinuxLinux994f706872e6ce080506bd795ecf783d5b617de6, 994f706872e6ce080506bd795ecf783d5b617de6, 994f706872e6ce080506bd795ecf783d5b617de6unaffected
LinuxLinux5.19, 0, 6.1.16, 6.2.3, 6.3affected
Weakness

CWE details

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