CVE-2026-98366 (GCVE-0-2026-98366)
Vulnerability from cvelistv5
Published
2026-10-06 08:46
Modified
2026-10-19 09:18
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c
Version: 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c
Version: 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c
Version: 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c
Version: 544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/sw/rxe/rxe_verbs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/sw/rxe/rxe_verbs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "lessThan": "6.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.54",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.158",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.54",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.8",
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                {
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: validate access flags before swapping the MR\u0027s PD\n\nrxe_rereg_user_mr() reassigns mr-\u003eibmr.pd first and only then\nvalidates the IB_MR_REREG_ACCESS argument:\n\n\tif (flags \u0026 IB_MR_REREG_PD) {\n\t\trxe_put(old_pd);\n\t\trxe_get(pd);\n\t\tmr-\u003eibmr.pd = ibpd;\n\t}\n\n\tif (flags \u0026 IB_MR_REREG_ACCESS) {\n\t\tif (access \u0026 ~RXE_ACCESS_SUPPORTED_MR)\n\t\t\treturn ERR_PTR(-EOPNOTSUPP);\n\t\tmr-\u003eaccess = access;\n\t}\n\nBoth flags pass the entry check because RXE_MR_REREG_SUPPORTED is\nIB_MR_REREG_PD | IB_MR_REREG_ACCESS, so a caller can reach the access\ncheck with mr-\u003eibmr.pd already reassigned.\n\nmr-\u003eibmr.pd is owned by the core, which adjusts pd-\u003eusecnt only on the\nsuccess path: ib_uverbs_rereg_mr() jumps to put_new_uobj on a driver error\nwithout undoing the reassignment, so mr-\u003epd == new_pd while the usecnts\nstill charge the MR to orig_pd. ib_dereg_mr_user() then decrements\nnew_pd, whose count can reach zero while a memory window still references\nit; uverbs_free_pd() frees the PD on that count alone and rxe_mw_cleanup()\nwrites to freed memory:\n\n  BUG: KASAN: slab-use-after-free in __rxe_put+0x31/0xa0\n  Write of size 4 at addr ffff8881301dd690 by task rxe_poc/591\n   __rxe_put+0x31/0xa0\n   rxe_mw_cleanup+0x42/0x200\n   __rxe_cleanup+0x115/0x370\n   rxe_dealloc_mw+0x4c/0x80\n  Allocated by task 591:\n   ib_uverbs_alloc_pd+0x258/0x540\n  Freed by task 591:\n   ib_dealloc_pd_user+0x174/0x210\n   uverbs_free_pd+0x8d/0xc0\n   ib_uverbs_dealloc_pd+0x18e/0x1d0\n\nValidate the access flags before mutating any state so the callback either\napplies every requested change or none."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bad access_flags/pd_handle reach rxe_rereg_user_mr() only through a local IB_USER_VERBS_CMD_REREG_MR on /dev/infiniband/uverbsN via ib_uverbs_rereg_mr(); no RoCE packet carries rereg arguments, so a remote peer cannot drive it.\nAC:L - Deterministic: flags IB_MR_REREG_PD|IB_MR_REREG_ACCESS with access=IB_ACCESS_RELAXED_ORDERING passes core ib_check_mr_access() but fails RXE_ACCESS_SUPPORTED_MR after mr-\u003eibmr.pd was swapped; the attacker then deregs the MR and deallocs the PD its own MW still uses. No race.\nPR:L - uverbs_devnode() creates /dev/infiniband/uverbsN mode 0666 and there is no capability check from ib_uverbs_rereg_mr() to rxe_rereg_user_mr(); any unprivileged local user owning a PD/MR/MW triggers it. Only the one-time admin rxe link creation (RDMA_NL_ADMIN_PERM) is needed.\nUI:N - The attacker\u0027s own process issues alloc_pd, reg_mr, alloc_mw, the failing rereg_mr, dereg_mr and dealloc_pd; no other user or administrator action is involved.\nS:U - The freed rxe PD and the corrupted refcounts are kernel heap objects within the same kernel security authority; no VM, IOMMU or sandbox boundary is crossed.\nC:H - After uverbs_free_pd() frees the PD on usecnt alone, the surviving MW still holds a dangling pointer to it; reclaiming that slab object with sprayed data turns later accesses through the MW into a use-after-free read of attacker-shaped memory.\nI:H - rxe_mw_cleanup() -\u003e __rxe_put() writes (refcount decrement, KASAN write of size 4) into the freed PD, and the inconsistent mr-\u003epd vs usecnt state can be repeated; a decrement into reallocated slab memory is a usable corruption primitive toward privilege escalation.\nA:H - The use-after-free write in __rxe_put() during rxe_dealloc_mw() corrupts freed slab memory and can oops or panic the kernel, and an unprivileged user can repeat it at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:18:18.297Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/08f12745cb72981aa2cabe214af0c7a42a856f0a"
        },
        {
          "url": "https://git.kernel.org/stable/c/7230cc456d4bb2221c20c5f1d22b38b8576aa16f"
        },
        {
          "url": "https://git.kernel.org/stable/c/fe602c91a52e161ace4afd5bdb8f33270c554c6f"
        },
        {
          "url": "https://git.kernel.org/stable/c/4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8"
        },
        {
          "url": "https://git.kernel.org/stable/c/ae36a5b609ae79f4de966328b78d2584be9719a4"
        }
      ],
      "title": "RDMA/rxe: validate access flags before swapping the MR\u0027s PD",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98366",
    "datePublished": "2026-10-06T08:46:51.638Z",
    "dateReserved": "2026-09-25T10:25:14.344Z",
    "dateUpdated": "2026-10-19T09:18:18.297Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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