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svcrdma: Reject Write/Reply chunks with segcount 0

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: svcrdma: Reject Write/Reply chunks with segcount 0 A peer can send a Write or Reply chunk whose segcount field is zero. xdr_check_write_chunk() only rejects segcount > rc_maxpages, so zero passes the range check, and xdr_inline_decode(stream, 0) returns the current (non-NULL) cursor without advancing. The function returns true and pcl_alloc_write() then links a struct svc_rdma_chunk with ch_segcount == 0 onto rc_write_pcl or rc_reply_pcl. An earlier patch in this series made pcl_for_each_segment() safe for ch_segcount == 0, so this no longer drives the memory walk it used to. Rejecting the malformed frame at the decode boundary is still worthwhile as defense in depth: it keeps degenerate zero-segment chunks off the parsed chunk lists entirely, so any future consumer that walks ch_segments directly cannot observe one, and it makes the zero-floor easy to backport to trees where the macro change is more intrusive. RFC 8166 has no meaning for a Write/Reply chunk that describes no remote buffer, so no legitimate client is affected. xdr_check_reply_chunk() funnels Reply chunks through xdr_check_write_chunk() and inherits the same rejection. pcl_alloc_write() also links each chunk onto the parsed chunk list before filling its segment array. If a future change weakens the segcount-0 rejection, an incomplete chunk is visible to consumers during the fill loop. Reorder so that list_add_tail() follows the segment fill lo

Announced Source revision 1
Original source ↗

CVE-2026-93228

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-93228

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
        "lessThan": "28c5a3a572f6cf81ac304459cfd515480995d62a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
        "lessThan": "fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
        "lessThan": "a798714b58041e88716db3bf8fb03ae13eecd54a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
        "lessThan": "45dbdb2637b7fc5f1355b588780d2a7fb0516805",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "78147ca8b4a9b6cf0e597ddd6bf17959e08376c2",
        "lessThan": "9808eb7656666acc7291bae9ab6b987bd16e47e0",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/sunrpc/xprtrdma/svc_rdma_pcl.c",
      "net/sunrpc/xprtrdma/svc_rdma_recvfrom.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.11"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.11",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.50",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/sunrpc/xprtrdma/svc_rdma_pcl.c",
      "net/sunrpc/xprtrdma/svc_rdma_recvfrom.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-93228

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#48738 · Revision 1
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Publisher date
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