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CVE Record

CVE-2025-38440: net/mlx5e: Fix race between DIM disable and net_dim()

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix race between DIM disable and net_dim() There's a race between disabling DIM and NAPI callbacks using the dim pointer on the RQ or SQ. If NAPI checks the DIM state bit and sees it still set, it assumes `rq->dim` or `sq->dim` is valid. But if DIM gets disabled right after that check, the pointer might already be set to NULL, leading to a NULL pointer dereference in net_dim(). Fix this by calling `synchronize_net()` before freeing the DIM context. This ensures all in-progress NAPI callbacks are finished before the pointer is cleared. Kernel log: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:net_dim+0x23/0x190 ... Call Trace: <TASK> ? __die+0x20/0x60 ? page_fault_oops+0x150/0x3e0 ? common_interrupt+0xf/0xa0 ? sysvec_call_function_single+0xb/0x90 ? exc_page_fault+0x74/0x130 ? asm_exc_page_fault+0x22/0x30 ? net_dim+0x23/0x190 ? mlx5e_poll_ico_cq+0x41/0x6f0 [mlx5_core] ? sysvec_apic_timer_interrupt+0xb/0x90 mlx5e_handle_rx_dim+0x92/0xd0 [mlx5_core] mlx5e_napi_poll+0x2cd/0xac0 [mlx5_core] ? mlx5e_poll_ico_cq+0xe5/0x6f0 [mlx5_core] busy_poll_stop+0xa2/0x200 ? mlx5e_napi_poll+0x1d9/0xac0 [mlx5_core] ? mlx5e_trigger_irq+0x130/0x130 [mlx5_core] __napi_busy_loop+0x345/0x3b0 ? sysvec_call_function_single+0xb/0x90 ? asm_sysvec_call_function_single+0x16/0x20 ? sysvec_apic_timer_interrupt+0xb/0x90 ? pcpu_free_area+0x1e4/0x2e0 napi_busy_loop+0x11/0x20 xsk_recvmsg+0x10c/0x130 sock_recvmsg+0x44/0x70 __sys_recvfrom+0xbc/0x130 ? __schedule+0x398/0x890 __x64_sys_recvfrom+0x20/0x30 do_syscall_64+0x4c/0x100 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ... ---[ end trace 0000000000000000 ]--- ... ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A timing flaw in the Linux mlx5e network driver can dereference a cleared pointer while processing network activity, causing a kernel crash. The demonstrated business impact is loss of availability on affected systems. The supplied CVSS score is 7.8, but exposure depends on the installed kernel and use of mlx5e hardware and DIM functionality.

Executive priority

Treat this as a high-priority availability issue for critical Linux systems using mlx5e networking. Patch confirmed-exposed hosts through normal kernel maintenance promptly, with accelerated handling where a kernel panic would disrupt essential services. Broad emergency action across unrelated Linux systems is not supported by the supplied evidence.

Technical view

NAPI may observe DIM as enabled while another path disables DIM, frees its context, and clears the RQ or SQ pointer. The callback can then pass NULL to net_dim(), producing a kernel panic. The upstream fix calls synchronize_net() before freeing the DIM context so active NAPI callbacks finish first.

Likely exposure

Potentially exposed systems run an affected Linux kernel with the mlx5e driver and DIM functionality in use. The supplied affected-version data includes 6.10, 6.12.39, 6.15.7, and 6.16, but branch boundaries are unclear; confirm exact status with the kernel or distribution vendor.

Exploitation context

The supplied CVSS vector describes local access, low privileges, low complexity, and no user interaction. No source in the bundle reports active exploitation, and the CVE is not identified as CISA KEV. The documented outcome is a NULL-pointer dereference and kernel panic during a DIM-disable race.

Researcher notes

The race is a lifetime-ordering defect between DIM teardown and NAPI callbacks. synchronize_net() supplies the required network-side quiescence before context release. The bundle demonstrates a crash but provides no exploit evidence or reliable distribution-specific affected matrix. Avoid inferring remote reachability or broader impact without additional vendor analysis.

Mitigation direction

  • Update to a vendor-supported kernel containing the referenced synchronization fix.
  • Confirm distribution backport status because package versions may differ from upstream kernel numbering.
  • Prioritize network-intensive or availability-critical hosts using the mlx5e driver.
  • Consult Linux or distribution guidance before considering operational workarounds.

Validation and detection

  • Inventory kernel versions and identify hosts using the mlx5e driver.
  • Map installed distribution packages to vendor advisories or fixed backports.
  • Review kernel logs for net_dim, mlx5e_napi_poll, NULL dereferences, or unexplained panics.
  • Verify the installed kernel incorporates one of the referenced stable commits or an equivalent backport.
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

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.

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CVE-2025-38440 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

1CVSS vectors
3Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-38440Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux445a25f6e1a2f6a132b06af6ede4f3c9b5f9af68, 445a25f6e1a2f6a132b06af6ede4f3c9b5f9af68, 445a25f6e1a2f6a132b06af6ede4f3c9b5f9af68unaffected
LinuxLinux6.10, 0, 6.12.39, 6.15.7, 6.16affected
Weakness

CWE details

No CWE listed

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