---
id: CVE-2026-98366
title: "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: validate access flags before swapping the MR's PD\n\nrxe_rereg_user_mr() reassigns mr->ibmr.pd first and only then\nvalidates the IB_MR_REREG_ACCESS argument:\n\n\t…"
summary: "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: validate access flags before swapping the MR's PD\n\nrxe_rereg_user_mr() reassigns mr->ibmr.pd first and only then\nvalidates the IB_MR_REREG_ACCESS argument:\n\n\t…"
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c <
    08f12745cb72981aa2cabe214af0c7a42a856f0a
  - >-
    Linux >= 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c <
    7230cc456d4bb2221c20c5f1d22b38b8576aa16f
  - >-
    Linux >= 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c <
    fe602c91a52e161ace4afd5bdb8f33270c554c6f
  - >-
    Linux >= 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c <
    4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8
  - >-
    Linux >= 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c <
    ae36a5b609ae79f4de966328b78d2584be9719a4
  - Linux 6.5
published: '2026-10-06'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T09:18:30.823'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98366'
references:
  - url: 'https://git.kernel.org/stable/c/08f12745cb72981aa2cabe214af0c7a42a856f0a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7230cc456d4bb2221c20c5f1d22b38b8576aa16f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ae36a5b609ae79f4de966328b78d2584be9719a4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fe602c91a52e161ace4afd5bdb8f33270c554c6f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-06T08:50:17.392Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

RDMA/rxe: validate access flags before swapping the MR's PD

rxe_rereg_user_mr() reassigns mr->ibmr.pd first and only then
validates the IB_MR_REREG_ACCESS argument:

	if (flags & IB_MR_REREG_PD) {
		rxe_put(old_pd);
		rxe_get(pd);
		mr->ibmr.pd = ibpd;
	}

	if (flags & IB_MR_REREG_ACCESS) {
		if (access & ~RXE_ACCESS_SUPPORTED_MR)
			return ERR_PTR(-EOPNOTSUPP);
		mr->access = access;
	}

Both flags pass the entry check because RXE_MR_REREG_SUPPORTED is
IB_MR_REREG_PD | IB_MR_REREG_ACCESS, so a caller can reach the access
check with mr->ibmr.pd already reassigned.

mr->ibmr.pd is owned by the core, which adjusts pd->usecnt only on the
success path: ib_uverbs_rereg_mr() jumps to put_new_uobj on a driver error
without undoing the reassignment, so mr->pd == new_pd while the usecnts
still charge the MR to orig_pd. ib_dereg_mr_user() then decrements
new_pd, whose count can reach zero while a memory window still references
it; uverbs_free_pd() frees the PD on that count alone and rxe_mw_cleanup()
writes to freed memory:

  BUG: KASAN: slab-use-after-free in __rxe_put+0x31/0xa0
  Write of size 4 at addr ffff8881301dd690 by task rxe_poc/591
   __rxe_put+0x31/0xa0
   rxe_mw_cleanup+0x42/0x200
   __rxe_cleanup+0x115/0x370
   rxe_dealloc_mw+0x4c/0x80
  Allocated by task 591:
   ib_uverbs_alloc_pd+0x258/0x540
  Freed by task 591:
   ib_dealloc_pd_user+0x174/0x210
   uverbs_free_pd+0x8d/0xc0
   ib_uverbs_dealloc_pd+0x18e/0x1d0

Validate the access flags before mutating any state so the callback either
applies every requested change or none.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.