CVE-2026-89742 is a vulnerability in Linux Kernel
Published on September 11, 2026
rapidio: mport_cdev: fix use-after-free in dma_req_free()
In the Linux kernel, the following vulnerability has been resolved:
rapidio: mport_cdev: fix use-after-free in dma_req_free()
dma_req_free() acquires buf_mutex through req->map, drops the mapping
reference with kref_put(), and then dereferences req->map again to unlock
the mutex.
If kref_put() drops the last reference, mport_release_mapping() frees the
mapping, and the subsequent mutex_unlock() dereferences a freed object.
This is a use-after-free.
Fix this by caching map and md before kref_put(), clearing req->map while
holding buf_mutex, and using the cached md for mutex unlocking.
The bug is reachable from userspace via the RapidIO mport character device
interface.
Products Associated with CVE-2026-89742
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Affected Versions
Linux:- Version e8de370188d098bb49483c287b44925957c3c9b6 and below 9a9929ec875ff20922c90c96fd544ae8a2a61a8d is affected.
- Version e8de370188d098bb49483c287b44925957c3c9b6 and below e6e925cc1f8067c65c7bec3da50a0ead3b3ef4e0 is affected.
- Version e8de370188d098bb49483c287b44925957c3c9b6 and below 211c68d817a3d9dc14c0026a59da7cac30f8147e is affected.
- Version e8de370188d098bb49483c287b44925957c3c9b6 and below 5cbef379a94b161726c5f504598bf4791d45cedc is affected.
- Version 4.6 is affected.
- Before 4.6 is unaffected.
- Version 6.12.109, <= 6.12.* is unaffected.
- Version 6.18.50, <= 6.18.* is unaffected.
- Version 7.2.4, <= 7.2.* is unaffected.
- Version 7.3-rc1, <= * is unaffected.