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GHSA-G3WM-757G-9P35

Vulnerability from github – Published: 2026-10-06 09:31 – Updated: 2026-10-07 09:32

Details

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

RDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths

Commit 0b261d7c1cd3 ("RDMA/rxe: Break endless pagefault loop for RO pages") dropped the access permission test from rxe_check_pagefault() and left only HMM_PFN_VALID. A page faulted in read-only, for example a page-cache folio behind a PROT_READ file mapping, then satisfies the check and ODP write operations (RDMA WRITE, RDMA READ response, SEND payload, atomics) modify it through kmap without ever breaking CoW.

An unprivileged user can register an ODP MR over such a mapping and have incoming RDMA traffic overwrite the page cache of a file it only holds O_RDONLY, including /etc/passwd or setuid binaries. This is the same primitive class as Dirty COW and CVE-2022-2590.

mlx5 has the missing invariant: its ODP path sets the device write bit only for pfns that carry HMM_PFN_WRITE. Restore it in rxe by requiring HMM_PFN_WRITE in rxe_check_pagefault() for every operation except RXE_PAGEFAULT_RDONLY. A write to a non-writable VMA now fails the one fault attempt with -EPERM from hmm_vma_fault() instead of re-faulting forever. For a writable VMA the fault breaks CoW and the write lands in the private page.

Keep pmem flushes on the read-only check. arch_wb_cache_pmem() never modifies memory, and the FLUSH access bits do not make the umem writable, so classifying flushes as writes would make every flush against a flush-only MR fail.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98361"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-06T09:18:29Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths\n\nCommit 0b261d7c1cd3 (\"RDMA/rxe: Break endless pagefault loop for RO\npages\") dropped the access permission test from rxe_check_pagefault()\nand left only HMM_PFN_VALID. A page faulted in read-only, for example\na page-cache folio behind a PROT_READ file mapping, then satisfies the\ncheck and ODP write operations (RDMA WRITE, RDMA READ response, SEND\npayload, atomics) modify it through kmap without ever breaking CoW.\n\nAn unprivileged user can register an ODP MR over such a mapping and\nhave incoming RDMA traffic overwrite the page cache of a file it only\nholds O_RDONLY, including /etc/passwd or setuid binaries. This is the\nsame primitive class as Dirty COW and CVE-2022-2590.\n\nmlx5 has the missing invariant: its ODP path sets the device write bit\nonly for pfns that carry HMM_PFN_WRITE. Restore it in rxe by requiring\nHMM_PFN_WRITE in rxe_check_pagefault() for every operation except\nRXE_PAGEFAULT_RDONLY. A write to a non-writable VMA now fails the one\nfault attempt with -EPERM from hmm_vma_fault() instead of re-faulting\nforever. For a writable VMA the fault breaks CoW and the write lands\nin the private page.\n\nKeep pmem flushes on the read-only check. arch_wb_cache_pmem() never\nmodifies memory, and the FLUSH access bits do not make the umem\nwritable, so classifying flushes as writes would make every flush\nagainst a flush-only MR fail.",
  "id": "GHSA-g3wm-757g-9p35",
  "modified": "2026-10-07T09:32:17Z",
  "published": "2026-10-06T09:31:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98361"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2d6c6f94d3e1cde049fe5db71dbd5549f10b2de1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/769001ce838d907ecaa95f1d0a4e8fc86f761f9f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c6f56982ec5c7da83c4bdfcce3b6db18bcfe6425"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-98361 (GCVE-0-2026-98361)

Vulnerability from cvelistv5 – Published: 2026-10-06 08:46 – Updated: 2026-10-07 06:50

Title

RDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths

Summary

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths Commit 0b261d7c1cd3 ("RDMA/rxe: Break endless pagefault loop for RO pages") dropped the access permission test from rxe_check_pagefault() and left only HMM_PFN_VALID. A page faulted in read-only, for example a page-cache folio behind a PROT_READ file mapping, then satisfies the check and ODP write operations (RDMA WRITE, RDMA READ response, SEND payload, atomics) modify it through kmap without ever breaking CoW. An unprivileged user can register an ODP MR over such a mapping and have incoming RDMA traffic overwrite the page cache of a file it only holds O_RDONLY, including /etc/passwd or setuid binaries. This is the same primitive class as Dirty COW and CVE-2022-2590. mlx5 has the missing invariant: its ODP path sets the device write bit only for pfns that carry HMM_PFN_WRITE. Restore it in rxe by requiring HMM_PFN_WRITE in rxe_check_pagefault() for every operation except RXE_PAGEFAULT_RDONLY. A write to a non-writable VMA now fails the one fault attempt with -EPERM from hmm_vma_fault() instead of re-faulting forever. For a writable VMA the fault breaks CoW and the write lands in the private page. Keep pmem flushes on the read-only check. arch_wb_cache_pmem() never modifies memory, and the FLUSH access bits do not make the umem writable, so classifying flushes as writes would make every flush against a flush-only MR fail.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root Scorecard

References

3 references

URL	Tags
https://git.kernel.org/stable/c/c6f56982ec5c7da83…
https://git.kernel.org/stable/c/2d6c6f94d3e1cde04…
https://git.kernel.org/stable/c/769001ce838d907ec…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 0b261d7c1cd32dc93cbc92425fb55e67b24c6638 , < c6f56982ec5c7da83c4bdfcce3b6db18bcfe6425 (git) Affected: 0b261d7c1cd32dc93cbc92425fb55e67b24c6638 , < 2d6c6f94d3e1cde049fe5db71dbd5549f10b2de1 (git) Affected: 0b261d7c1cd32dc93cbc92425fb55e67b24c6638 , < 769001ce838d907ecaa95f1d0a4e8fc86f761f9f (git)
Linux	Linux	Affected: 6.16 Unaffected: 0 , < 6.16 (semver) Unaffected: 6.18.54 , ≤ 6.18.* (semver) Unaffected: 7.2.8 , ≤ 7.2.* (semver) Unaffected: 7.3-rc4 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/sw/rxe/rxe_odp.c"
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          "versions": [
            {
              "lessThan": "c6f56982ec5c7da83c4bdfcce3b6db18bcfe6425",
              "status": "affected",
              "version": "0b261d7c1cd32dc93cbc92425fb55e67b24c6638",
              "versionType": "git"
            },
            {
              "lessThan": "2d6c6f94d3e1cde049fe5db71dbd5549f10b2de1",
              "status": "affected",
              "version": "0b261d7c1cd32dc93cbc92425fb55e67b24c6638",
              "versionType": "git"
            },
            {
              "lessThan": "769001ce838d907ecaa95f1d0a4e8fc86f761f9f",
              "status": "affected",
              "version": "0b261d7c1cd32dc93cbc92425fb55e67b24c6638",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/sw/rxe/rxe_odp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "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-rc4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.54",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc4",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths\n\nCommit 0b261d7c1cd3 (\"RDMA/rxe: Break endless pagefault loop for RO\npages\") dropped the access permission test from rxe_check_pagefault()\nand left only HMM_PFN_VALID. A page faulted in read-only, for example\na page-cache folio behind a PROT_READ file mapping, then satisfies the\ncheck and ODP write operations (RDMA WRITE, RDMA READ response, SEND\npayload, atomics) modify it through kmap without ever breaking CoW.\n\nAn unprivileged user can register an ODP MR over such a mapping and\nhave incoming RDMA traffic overwrite the page cache of a file it only\nholds O_RDONLY, including /etc/passwd or setuid binaries. This is the\nsame primitive class as Dirty COW and CVE-2022-2590.\n\nmlx5 has the missing invariant: its ODP path sets the device write bit\nonly for pfns that carry HMM_PFN_WRITE. Restore it in rxe by requiring\nHMM_PFN_WRITE in rxe_check_pagefault() for every operation except\nRXE_PAGEFAULT_RDONLY. A write to a non-writable VMA now fails the one\nfault attempt with -EPERM from hmm_vma_fault() instead of re-faulting\nforever. For a writable VMA the fault breaks CoW and the write lands\nin the private page.\n\nKeep pmem flushes on the read-only check. arch_wb_cache_pmem() never\nmodifies memory, and the FLUSH access bits do not make the umem\nwritable, so classifying flushes as writes would make every flush\nagainst a flush-only MR fail."
        }
      ],
      "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 bug needs an ODP MR with remote write access, created by a local user through uverbs reg_user_mr (rxe_reg_user_mr -\u003e rxe_odp_mr_init_user) over their own PROT_READ file mapping. The RDMA WRITE/SEND/atomic that reaches rxe_odp_map_range_and_lock can come from the same user\u0027s QP on the same rxe device, and a remote peer cannot set up this state on its own.\nAC:L - Once an rxe device exists, the attacker controls every step: mmap a readable file PROT_READ, fault the pages in read-only, register the MR so the snapshot rxe_odp_init_pages() records them HMM_PFN_VALID without WRITE, then post an RDMA WRITE to it. rxe_check_pagefault() only tested VALID, so the result is deterministic with no race.\nPR:L - Registering an MR and QPs on /dev/infiniband/uverbs* needs no capability, and the device is normally world-accessible. Only creating the rxe link (rdma link add, RDMA_NL_ADMIN_PERM) needs CAP_NET_ADMIN in init_user_ns. The attacker needs only read access to the target file.\nUI:N - The attacker does everything with their own syscalls and RDMA operations on mappings they own; no other user or admin has to act at the time of the attack.\nS:U - The impact is writes to the page cache through kmap_local_page in __rxe_odp_mr_copy, inside the same kernel authority. It is a standard local privilege escalation and crosses no VM or IOMMU boundary.\nC:H - Overwriting the cached contents of root-owned files the user can only read (/etc/passwd, /etc/shadow handling, setuid binaries) leads to root, which exposes all data on the system, as with Dirty COW and CVE-2022-2590.\nI:H - __rxe_odp_mr_copy (RXE_TO_MR_OBJ) and rxe_odp_do_atomic_op/atomic_write write attacker-chosen bytes into read-only page-cache folios without breaking CoW, so arbitrary file contents can be modified and setuid binaries rewritten for code execution as root.\nA:H - With write access to the page cache of system binaries and libraries, the attacker can corrupt critical files such as init and libc, or take root, and make the system unusable."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-07T06:50:16.164Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/c6f56982ec5c7da83c4bdfcce3b6db18bcfe6425"
        },
        {
          "url": "https://git.kernel.org/stable/c/2d6c6f94d3e1cde049fe5db71dbd5549f10b2de1"
        },
        {
          "url": "https://git.kernel.org/stable/c/769001ce838d907ecaa95f1d0a4e8fc86f761f9f"
        }
      ],
      "title": "RDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98361",
    "datePublished": "2026-10-06T08:46:47.600Z",
    "dateReserved": "2026-09-25T10:25:14.344Z",
    "dateUpdated": "2026-10-07T06:50:16.164Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-G3WM-757G-9P35

CVE-2026-98361 (GCVE-0-2026-98361)

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