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CVE Record

CVE-2023-53558: rcu-tasks: Avoid pr_info() with spin lock in cblist_init_generic()

In the Linux kernel, the following vulnerability has been resolved: rcu-tasks: Avoid pr_info() with spin lock in cblist_init_generic() pr_info() is called with rtp->cbs_gbl_lock spin lock locked. Because pr_info() calls printk() that might sleep, this will result in BUG like below: [ 0.206455] cblist_init_generic: Setting adjustable number of callback queues. [ 0.206463] [ 0.206464] ============================= [ 0.206464] [ BUG: Invalid wait context ] [ 0.206465] 5.19.0-00428-g9de1f9c8ca51 #5 Not tainted [ 0.206466] ----------------------------- [ 0.206466] swapper/0/1 is trying to lock: [ 0.206467] ffffffffa0167a58 (&port_lock_key){....}-{3:3}, at: serial8250_console_write+0x327/0x4a0 [ 0.206473] other info that might help us debug this: [ 0.206473] context-{5:5} [ 0.206474] 3 locks held by swapper/0/1: [ 0.206474] #0: ffffffff9eb597e0 (rcu_tasks.cbs_gbl_lock){....}-{2:2}, at: cblist_init_generic.constprop.0+0x14/0x1f0 [ 0.206478] #1: ffffffff9eb579c0 (console_lock){+.+.}-{0:0}, at: _printk+0x63/0x7e [ 0.206482] #2: ffffffff9ea77780 (console_owner){....}-{0:0}, at: console_emit_next_record.constprop.0+0x111/0x330 [ 0.206485] stack backtrace: [ 0.206486] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-00428-g9de1f9c8ca51 #5 [ 0.206488] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 [ 0.206489] Call Trace: [ 0.206490] <TASK> [ 0.206491] dump_stack_lvl+0x6a/0x9f [ 0.206493] __lock_acquire.cold+0x2d7/0x2fe [ 0.206496] ? stack_trace_save+0x46/0x70 [ 0.206497] lock_acquire+0xd1/0x2f0 [ 0.206499] ? serial8250_console_write+0x327/0x4a0 [ 0.206500] ? __lock_acquire+0x5c7/0x2720 [ 0.206502] _raw_spin_lock_irqsave+0x3d/0x90 [ 0.206504] ? serial8250_console_write+0x327/0x4a0 [ 0.206506] serial8250_console_write+0x327/0x4a0 [ 0.206508] console_emit_next_record.constprop.0+0x180/0x330 [ 0.206511] console_unlock+0xf7/0x1f0 [ 0.206512] vprintk_emit+0xf7/0x330 [ 0.206514] _printk+0x63/0x7e [ 0.206516] cblist_init_generic.constprop.0.cold+0x24/0x32 [ 0.206518] rcu_init_tasks_generic+0x5/0xd9 [ 0.206522] kernel_init_freeable+0x15b/0x2a2 [ 0.206523] ? rest_init+0x160/0x160 [ 0.206526] kernel_init+0x11/0x120 [ 0.206527] ret_from_fork+0x1f/0x30 [ 0.206530] </TASK> [ 0.207018] cblist_init_generic: Setting shift to 1 and lim to 1. This patch moves pr_info() so that it is called without rtp->cbs_gbl_lock locked.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue is a reliability bug in early RCU task initialization. A log message was emitted while a spin lock was held, and the logging path could sleep, triggering a kernel BUG warning. The sources do not show remote attack capability, active exploitation, or a CVSS score.

Executive priority

Handle through normal kernel patch management unless your distribution assigns higher severity. Current public evidence does not support emergency response, but availability-sensitive fleets should confirm whether affected kernels are deployed.

Technical view

In rcu-tasks cblist_init_generic(), pr_info() called printk() while rtp->cbs_gbl_lock was held. Because printk() may sleep, lock debugging reported an invalid wait context. The referenced kernel patches move the pr_info() call outside the locked region.

Likely exposure

Exposure is limited to Linux kernels matching the affected ranges or commits listed in the CVE data. The bundle identifies Linux kernel versions including 5.17, 6.1.42, 6.4.7, and 6.5, but distro-specific backport status is not provided.

Exploitation context

The source bundle marks KEV as false and provides no evidence of active exploitation. The described failure is a kernel locking-context bug observable through BUG diagnostics, not a documented attacker-driven exploit path.

Researcher notes

The core issue is lock-context correctness: printk() may enter paths that sleep while cbs_gbl_lock is held. The fix is narrowly scoped to logging placement. The bundle lacks CVSS, CWE, exploitability analysis, and distro backport details.

Mitigation direction

  • Check Linux vendor advisories for kernels containing the referenced stable fixes.
  • Update affected systems to a vendor-supported kernel with the RCU tasks fix.
  • Prioritize internet-facing or availability-sensitive hosts if your vendor rates this higher.
  • Avoid inventing workarounds; follow kernel or distribution guidance.

Validation and detection

  • Inventory running Linux kernel versions across servers and appliances.
  • Compare versions against distro advisories and the referenced upstream stable commits.
  • Review boot or kernel logs for invalid wait context messages in cblist_init_generic().
  • Confirm the installed kernel includes the patch moving pr_info() outside the lock.
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

    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
LinuxLinuxab97152f88a4d580b89f0b7cc3028ffac438216f, ab97152f88a4d580b89f0b7cc3028ffac438216f, ab97152f88a4d580b89f0b7cc3028ffac438216funaffected
LinuxLinux5.17, 0, 6.1.42, 6.4.7, 6.5affected
Weakness

CWE details

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