CVE-2026-98344
dmaengine: Fix device kref underflow in dma_chan_put()
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.
INFO
Published Date :
Oct. 6, 2026, 9:18 a.m.
Last Modified :
Oct. 6, 2026, 9:18 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Ensure device->ref is dropped only on the last put.
- Apply the kernel patch addressing dma_chan_put() and dma_device_get().
- Update the Linux kernel to the patched version.
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associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
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Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Oct. 06, 2026
Action Type Old Value New Value Added 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/98xxx/CVE-2026-98344.json">CVE-2026-98344</a> Added Reference https://git.kernel.org/stable/c/036b527f92570206da4b8c40b38f8d689e29d0f3 Added Reference https://git.kernel.org/stable/c/1a0d9b406febf23054ad595fd47b29325e70fb2d Added Reference https://git.kernel.org/stable/c/44dab659064eb5c10adb0306510eebe848ed592d Added Reference https://git.kernel.org/stable/c/57f7f1c6827be7d8f80feca48d2125fb91c6f6ed Added Reference https://git.kernel.org/stable/c/5fb1797a8c9485e40e5492fa0338ab5c7d1f3fef Added Reference https://git.kernel.org/stable/c/77906ac448d2fa81fa710ae26c0e591ebdc81154 Added Reference https://git.kernel.org/stable/c/7c3f4ce651d43705f9ec7f778f642a90d5ff4fba Added Reference https://git.kernel.org/stable/c/de2677e57d3161390d8a508f08cddec6ef7e4b23