HIGH
rdma CQDestroy UAF
CVE-2026-92508
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
KernelScan AI7.0HIGH
01Description
In the Linux kernel, the following vulnerability has been resolved: RDMA/core: Fix potential use after free in ib_free_cq() When accessing a CQ via the netlink path the only synchronization mechanism for the said CQ is rdma_restrack_get(). Currently, rdma_restrack_del() is invoked at the end of ib_free_cq(), which is too late, since by that point vendor-specific resources associated with the CQ might already be freed. This can leave a short window where the CQ remains accessible through restrack, leading to a potential use-after-free. Fix this by moving the rdma_restrack_del() call to be before the freeing of the vendor-specific resources ensuring that the CQ is removed from restrack before its internal resources are released. This guarantees that no new users hold references to a CQ that is in the process of destruction.
02KernelScan AI Analysis
Risk summary
A local attacker with access to RDMA devices can exploit a race condition during completion queue destruction, where the CQ remains visible through the resource tracking netlink interface after its internal resources are already freed. This can lead to use-after-free with potential for information disclosure, memory corruption, or denial of service. Systems with RDMA hardware or software drivers (rxe, siw) are affected.
Vulnerability analysis
During completion queue destruction, the RDMA resource tracking entry is removed too late—after vendor-specific resources have already been torn down. This leaves a window where a concurrent netlink query can still discover and obtain a reference to the CQ through resource tracking, but the CQ's internal resources are already gone, resulting in a use-after-free. The fix moves the resource tracking removal to the beginning of the destruction sequence, before any vendor resources are released, ensuring no new references can be acquired once teardown begins. The vulnerability is reachable locally by any user who can create and destroy RDMA completion queues while a concurrent restrack netlink query is in flight; it requires RDMA hardware or a software RDMA driver to be loaded.
Lifecycle
03Fix Versions
| Branch | Introduced | Fixed in | Patch commit |
|---|---|---|---|
| 5.8 | 5.8.17 | 5.9 | a804b162f9bc |
| 5.15 | — | 5.15.221 | 76f2cb4f7218 |
| 6.1 | — | 6.1.188 | b8dcca427096 |
| 6.6 | — | 6.6.157 | 9abea3794253 |
| 6.12 | — | 6.12.110 | 43403fe45379 |
| 6.18 | — | 6.18.52 | 29dc2f8e1c97 |
| 7.2 | — | 7.2.6 | — |
| mainline | — | 7.3-rc1 | — |
| 5.9 | 5.9.2 | 5.10 | 91f8a17a22ab |
| cip/6.12 | — | 6.12.111-cip32 | b8dcca427096 |