CVE-2026-89742
Published: September 15, 2026Last modified: September 15, 2026
Description
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.8 |
| Attack Vector | LOCAL |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity impact | HIGH |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | linux-lts | Vulnerable (6.1.182-r0) |
| 25 LTS | linux-lts | Vulnerable (6.12.103-r0) | |
| Stream | linux-lts | Vulnerable (6.18.46-r0) |
References
- https://git.kernel.org/stable/c/00c5ed913b0dc563fbeb8a97ea8916c03bbbbf6a
- https://git.kernel.org/stable/c/211c68d817a3d9dc14c0026a59da7cac30f8147e
- https://git.kernel.org/stable/c/26ccfe7d69e27b0d933ae0a64a23a0cb9b9a85a6
- https://git.kernel.org/stable/c/5cbef379a94b161726c5f504598bf4791d45cedc
- https://git.kernel.org/stable/c/9a9929ec875ff20922c90c96fd544ae8a2a61a8d
- https://git.kernel.org/stable/c/bd8881c24a9520f9c3d3e855d866197f63e471a7
- https://git.kernel.org/stable/c/e6e925cc1f8067c65c7bec3da50a0ead3b3ef4e0
- https://git.kernel.org/stable/c/fc79c07cdcde02c5b17633d78777de6ac2c14b29