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FKIE_CVE-2026-89532

Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-09-14 13:19
Severity
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: svcrdma: Fix pcl_for_each_segment for empty chunks When a parsed chunk list contains a chunk whose ch_segcount is zero, pcl_for_each_segment computes its inclusive upper bound as &chunk->ch_segments[ch_segcount - 1]. ch_segcount is u32, so the subtraction wraps to 0xFFFFFFFF and the bound lands far past the ch_segments flex array. The loop body then walks unrelated memory at sizeof(struct svc_rdma_segment) stride until it faults. A zero-segcount chunk is reachable from the wire: xdr_check_write_chunk() only rejects segcount values greater than rc_maxpages, and pcl_alloc_write() links a freshly allocated chunk onto rc_write_pcl/rc_reply_pcl before its segment-fill loop runs, so a Write or Reply chunk advertising zero segments leaves ch_segcount == 0 on the list. When the transport has negotiated Send-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four PCLs with pcl_for_each_segment and dereferences segment->rs_handle on each iteration, turning the underflow into an out-of-bounds read and a general protection fault. xdr_check_write_list / xdr_check_reply_chunk pcl_alloc_write() chunk = pcl_alloc_chunk(...) /* ch_segcount = 0 */ list_add_tail(&chunk->ch_list, &pcl->cl_chunks) /* fill loop iterates zero times for wire segcount 0 */ svc_rdma_get_inv_rkey() pcl_for_each_chunk(rc_write_pcl) pcl_for_each_segment(segment, chunk) pos <= &ch_segments[0u - 1u] /* 0xFFFFFFFF */ segment->rs_handle /* OOB read -> GPF */ Fix by switching the macro to a half-open upper bound that uses ch_segcount directly. For ch_segcount == 0 the loop start equals the loop end and the body is skipped; for ch_segcount > 0 the iteration range is unchanged. All six existing call sites in net/sunrpc/xprtrdma/svc_rdma_recvfrom.c and net/sunrpc/xprtrdma/svc_rdma_rw.c remain correct under the new bound, so no caller changes are needed.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/06d0390c37fa6714624af771bd72bbf1a7ed9bb1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1e2e3481e39103a386b86be1c33eaef97cbdf16e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3a78b841879c2a3243f74edc514236fb2907167f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6d33a7e6bf6c6b293a266a617201285a1ad32c56
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9c5a03c3dc505c0295339b0a1b9e4fe36447e482
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b7713a784c59515d0aba558c8f5df6a0164dd3a9
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/sunrpc/svc_rdma_pcl.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "1e2e3481e39103a386b86be1c33eaef97cbdf16e",
              "status": "affected",
              "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
              "versionType": "git"
            },
            {
              "lessThan": "3a78b841879c2a3243f74edc514236fb2907167f",
              "status": "affected",
              "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
              "versionType": "git"
            },
            {
              "lessThan": "06d0390c37fa6714624af771bd72bbf1a7ed9bb1",
              "status": "affected",
              "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
              "versionType": "git"
            },
            {
              "lessThan": "9c5a03c3dc505c0295339b0a1b9e4fe36447e482",
              "status": "affected",
              "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
              "versionType": "git"
            },
            {
              "lessThan": "a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8",
              "status": "affected",
              "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
              "versionType": "git"
            },
            {
              "lessThan": "6d33a7e6bf6c6b293a266a617201285a1ad32c56",
              "status": "affected",
              "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
              "versionType": "git"
            },
            {
              "lessThan": "b7713a784c59515d0aba558c8f5df6a0164dd3a9",
              "status": "affected",
              "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/sunrpc/svc_rdma_pcl.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.11"
            },
            {
              "lessThan": "5.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Fix pcl_for_each_segment for empty chunks\n\nWhen a parsed chunk list contains a chunk whose ch_segcount is zero,\npcl_for_each_segment computes its inclusive upper bound as\n\u0026chunk-\u003ech_segments[ch_segcount - 1]. ch_segcount is u32, so the\nsubtraction wraps to 0xFFFFFFFF and the bound lands far past the\nch_segments flex array. The loop body then walks unrelated memory at\nsizeof(struct svc_rdma_segment) stride until it faults.\n\nA zero-segcount chunk is reachable from the wire:\nxdr_check_write_chunk() only rejects segcount values greater than\nrc_maxpages, and pcl_alloc_write() links a freshly allocated chunk\nonto rc_write_pcl/rc_reply_pcl before its segment-fill loop runs,\nso a Write or Reply chunk advertising zero segments leaves\nch_segcount == 0 on the list. When the transport has negotiated\nSend-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four\nPCLs with pcl_for_each_segment and dereferences segment-\u003ers_handle\non each iteration, turning the underflow into an out-of-bounds read\nand a general protection fault.\n\n    xdr_check_write_list / xdr_check_reply_chunk\n      pcl_alloc_write()\n        chunk = pcl_alloc_chunk(...)  /* ch_segcount = 0 */\n        list_add_tail(\u0026chunk-\u003ech_list, \u0026pcl-\u003ecl_chunks)\n        /* fill loop iterates zero times for wire segcount 0 */\n\n    svc_rdma_get_inv_rkey()\n      pcl_for_each_chunk(rc_write_pcl)\n        pcl_for_each_segment(segment, chunk)\n          pos \u003c= \u0026ch_segments[0u - 1u]  /* 0xFFFFFFFF */\n          segment-\u003ers_handle            /* OOB read -\u003e GPF */\n\nFix by switching the macro to a half-open upper bound that uses\nch_segcount directly. For ch_segcount == 0 the loop start equals the\nloop end and the body is skipped; for ch_segcount \u003e 0 the iteration\nrange is unchanged. All six existing call sites in\nnet/sunrpc/xprtrdma/svc_rdma_recvfrom.c and\nnet/sunrpc/xprtrdma/svc_rdma_rw.c remain correct under the new bound,\nso no caller changes are needed."
    }
  ],
  "id": "CVE-2026-89532",
  "lastModified": "2026-09-14T13:19:08.400",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-11T20:19:36.117",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/06d0390c37fa6714624af771bd72bbf1a7ed9bb1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1e2e3481e39103a386b86be1c33eaef97cbdf16e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3a78b841879c2a3243f74edc514236fb2907167f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6d33a7e6bf6c6b293a266a617201285a1ad32c56"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9c5a03c3dc505c0295339b0a1b9e4fe36447e482"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b7713a784c59515d0aba558c8f5df6a0164dd3a9"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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