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CVE Record

CVE-2024-40980: drop_monitor: replace spin_lock by raw_spin_lock

In the Linux kernel, the following vulnerability has been resolved: drop_monitor: replace spin_lock by raw_spin_lock trace_drop_common() is called with preemption disabled, and it acquires a spin_lock. This is problematic for RT kernels because spin_locks are sleeping locks in this configuration, which causes the following splat: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 449, name: rcuc/47 preempt_count: 1, expected: 0 RCU nest depth: 2, expected: 2 5 locks held by rcuc/47/449: #0: ff1100086ec30a60 ((softirq_ctrl.lock)){+.+.}-{2:2}, at: __local_bh_disable_ip+0x105/0x210 #1: ffffffffb394a280 (rcu_read_lock){....}-{1:2}, at: rt_spin_lock+0xbf/0x130 #2: ffffffffb394a280 (rcu_read_lock){....}-{1:2}, at: __local_bh_disable_ip+0x11c/0x210 #3: ffffffffb394a160 (rcu_callback){....}-{0:0}, at: rcu_do_batch+0x360/0xc70 #4: ff1100086ee07520 (&data->lock){+.+.}-{2:2}, at: trace_drop_common.constprop.0+0xb5/0x290 irq event stamp: 139909 hardirqs last enabled at (139908): [<ffffffffb1df2b33>] _raw_spin_unlock_irqrestore+0x63/0x80 hardirqs last disabled at (139909): [<ffffffffb19bd03d>] trace_drop_common.constprop.0+0x26d/0x290 softirqs last enabled at (139892): [<ffffffffb07a1083>] __local_bh_enable_ip+0x103/0x170 softirqs last disabled at (139898): [<ffffffffb0909b33>] rcu_cpu_kthread+0x93/0x1f0 Preemption disabled at: [<ffffffffb1de786b>] rt_mutex_slowunlock+0xab/0x2e0 CPU: 47 PID: 449 Comm: rcuc/47 Not tainted 6.9.0-rc2-rt1+ #7 Hardware name: Dell Inc. PowerEdge R650/0Y2G81, BIOS 1.6.5 04/15/2022 Call Trace: <TASK> dump_stack_lvl+0x8c/0xd0 dump_stack+0x14/0x20 __might_resched+0x21e/0x2f0 rt_spin_lock+0x5e/0x130 ? trace_drop_common.constprop.0+0xb5/0x290 ? skb_queue_purge_reason.part.0+0x1bf/0x230 trace_drop_common.constprop.0+0xb5/0x290 ? preempt_count_sub+0x1c/0xd0 ? _raw_spin_unlock_irqrestore+0x4a/0x80 ? __pfx_trace_drop_common.constprop.0+0x10/0x10 ? rt_mutex_slowunlock+0x26a/0x2e0 ? skb_queue_purge_reason.part.0+0x1bf/0x230 ? __pfx_rt_mutex_slowunlock+0x10/0x10 ? skb_queue_purge_reason.part.0+0x1bf/0x230 trace_kfree_skb_hit+0x15/0x20 trace_kfree_skb+0xe9/0x150 kfree_skb_reason+0x7b/0x110 skb_queue_purge_reason.part.0+0x1bf/0x230 ? __pfx_skb_queue_purge_reason.part.0+0x10/0x10 ? mark_lock.part.0+0x8a/0x520 ... trace_drop_common() also disables interrupts, but this is a minor issue because we could easily replace it with a local_lock. Replace the spin_lock with raw_spin_lock to avoid sleeping in atomic context.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's Takeunknown

Analyst readout for executives and security teams

Plain-English summary

CVE-2024-40980 is a Linux kernel locking bug in drop_monitor. On real-time kernels, code can try to take a lock that may sleep while preemption is disabled, causing a kernel warning or instability. Sources do not provide CVSS, confirmed exploitation, or broad impact detail.

Executive priority

Do not treat this as an emergency based on the provided evidence. Treat it as a targeted kernel-stability issue, with higher urgency for production real-time Linux, industrial systems, and appliances covered by vendor advisories.

Technical view

trace_drop_common() runs with preemption disabled and used spin_lock. On RT kernels, spin_locks can sleep, which is invalid in atomic context. The kernel fix replaces spin_lock with raw_spin_lock for the drop_monitor data lock. Evidence centers on PREEMPT_RT behavior and kernel stability, not remote exploitation.

Likely exposure

Exposure is most relevant to Linux systems using RT kernels or vendor products that include affected Linux kernels. General Linux fleets should still check vendor kernel advisories because the affected-version data in the source bundle is not detailed enough to prove safe versions alone.

Exploitation context

The source bundle does not show CISA KEV listing or any cited active exploitation. The described failure is a kernel locking-context bug triggered during packet-drop tracing paths, with evidence of a BUG splat on a 6.9.0-rc2-rt1 kernel.

Researcher notes

The record lacks CVSS, CWE, and exploit evidence. The useful technical anchor is the locking change in trace_drop_common(): spin_lock to raw_spin_lock because RT spin_locks can sleep. Validate against exact vendor kernel trees rather than relying on the flattened affected-version list.

Mitigation direction

  • Apply Linux kernel updates that include the referenced stable commits.
  • Use distribution or appliance vendor advisories for exact fixed packages.
  • Prioritize real-time Linux, industrial, and embedded systems first.
  • For Siemens products, follow the cited Siemens ProductCERT advisories.
  • If no vendor fix is available, monitor vendor guidance closely.

Validation and detection

  • Inventory Linux kernel versions and RT/PREEMPT_RT usage.
  • Check vendor changelogs for CVE-2024-40980 or referenced commit IDs.
  • Review kernel logs for sleeping-function invalid-context warnings in drop_monitor paths.
  • Confirm updated systems run vendor-fixed kernel builds.
  • Track Debian LTS and product advisories for package-specific status.
Prepared
Confidence
medium
Sources
12

Public sources used

Based on public source material and reviewed before publication.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2024-40980 mapping review

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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
3ADP providers
12Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

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

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4ea7e38696c7e798c47ebbecadfd392f23f814f9, 4ea7e38696c7e798c47ebbecadfd392f23f814f9, 4ea7e38696c7e798c47ebbecadfd392f23f814f9, 4ea7e38696c7e798c47ebbecadfd392f23f814f9, 4ea7e38696c7e798c47ebbecadfd392f23f814f9, 4ea7e38696c7e798c47ebbecadfd392f23f814f9, 4ea7e38696c7e798c47ebbecadfd392f23f814f9unaffected
LinuxLinux2.6.31, 0, 5.4.279, 5.10.221, 5.15.162, 6.1.96, 6.6.36, 6.9.7, 6.10affected
Weakness

CWE details

No CWE listed

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