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CVE Record

CVE-2025-71221: dmaengine: mmp_pdma: Fix race condition in mmp_pdma_residue()

In the Linux kernel, the following vulnerability has been resolved: dmaengine: mmp_pdma: Fix race condition in mmp_pdma_residue() Add proper locking in mmp_pdma_residue() to prevent use-after-free when accessing descriptor list and descriptor contents. The race occurs when multiple threads call tx_status() while the tasklet on another CPU is freeing completed descriptors: CPU 0 CPU 1 ----- ----- mmp_pdma_tx_status() mmp_pdma_residue() -> NO LOCK held list_for_each_entry(sw, ..) DMA interrupt dma_do_tasklet() -> spin_lock(&desc_lock) list_move(sw->node, ...) spin_unlock(&desc_lock) | dma_pool_free(sw) <- FREED! -> access sw->desc <- UAF! This issue can be reproduced when running dmatest on the same channel with multiple threads (threads_per_chan > 1). Fix by protecting the chain_running list iteration and descriptor access with the chan->desc_lock spinlock.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

A Linux kernel DMA driver race can let one CPU read freed memory while another frees completed transfer descriptors. The published scenario uses concurrent DMA status checks and completion handling. Business impact is likely availability or stability risk on systems using affected mmp_pdma support, but public sources do not provide CVSS, exploitability, or confirmed exploitation.

Executive priority

Treat this as a targeted kernel maintenance issue, not an emergency internet-wide event based on current evidence. Prioritize embedded, industrial, or appliance environments that use affected Linux kernels and DMA hardware paths.

Technical view

mmp_pdma_residue() iterated chain_running and read descriptors without chan->desc_lock. Concurrent tx_status() calls could race with DMA tasklet cleanup moving and freeing descriptors, causing a use-after-free. The kernel fix protects the list walk and descriptor access with desc_lock. Reproduction evidence is limited to dmatest with multiple threads on the same channel.

Likely exposure

Exposure appears limited to Linux systems running affected kernels with the mmp_pdma dmaengine driver relevant to their hardware or product build. The bundle lists Linux kernel affected ranges and Siemens advisories, but does not identify specific Siemens product impact details.

Exploitation context

The source bundle says KEV is false and provides no evidence of active exploitation. The described trigger is a race during concurrent DMA status checking and descriptor cleanup, reproduced with dmatest using multiple threads on one channel.

Researcher notes

The key primitive is a use-after-free in mmp_pdma_residue() caused by missing desc_lock coverage around chain_running traversal and descriptor reads. Evidence does not establish privilege impact, code execution, or remote reachability. Avoid assuming impact beyond affected kernel builds and products named by vendors.

Mitigation direction

  • Update to a kernel build containing the referenced stable fixes.
  • For vendor appliances, follow the linked Siemens product advisories.
  • Prioritize systems where mmp_pdma support is enabled and reachable.
  • If no update is available, monitor vendor guidance for compensating controls.

Validation and detection

  • Inventory Linux kernel versions across affected device classes.
  • Check whether the mmp_pdma driver is built or loaded.
  • Map installed kernels against the referenced stable commits.
  • Review Siemens advisories for product-specific applicability.
  • Confirm vendor-supplied kernel packages include the locking fix.
Prepared
Confidence
medium
Sources
10

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

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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
1ADP providers
9Source 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

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

ADP provider summaries

siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1b38da264674d6a0fe26a63996b8f88b88c3da48, 1b38da264674d6a0fe26a63996b8f88b88c3da48, 1b38da264674d6a0fe26a63996b8f88b88c3da48, 1b38da264674d6a0fe26a63996b8f88b88c3da48, 1b38da264674d6a0fe26a63996b8f88b88c3da48, 1b38da264674d6a0fe26a63996b8f88b88c3da48unaffected
LinuxLinux3.16, 0, 5.15.209, 6.1.167, 6.6.130, 6.12.78, 6.18.10, 6.19affected
Weakness

CWE details

No CWE listed

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