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ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment smb2_get_ea() applies 4-byte alignment padding via memset() after writing each EA entry. The bounds check on buf_free_len is performed before the value memcpy, but the alignment memset fires unconditionally afterward with no check on remaining space. When the EA value exactly fills the remaining buffer (buf_free_len == 0 after value subtraction), the alignment memset writes 1-3 NUL bytes past the buf_free_len boundary. In compound requests where the response buffer is shared across commands, the first command (e.g., READ) can consume most of the buffer, leaving a tight remainder for the QUERY_INFO EA response. The alignment memset then overwrites past the physical kvmalloc allocation into adjacent kernel heap memory. Add a bounds check before the alignment memset to ensure buf_free_len can accommodate the padding bytes. This is the same bug pattern fixed by commit beef2634f81f ("ksmbd: fix potencial OOB in get_file_all_info() for compound requests") and commit fda9522ed6af ("ksmbd: fix OOB write in QUERY_INFO for compound requests"), both of which added bounds checks before unconditional writes in QUERY_INFO response handlers.

Announced Source revision 1
Original source ↗

CVE-2026-31705

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-2026-31705

Linux

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

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

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": "9f297df20d93411c0b4ddad7f88ba04a7cd36e77",
        "lessThan": "ddbbc8b2a09dd2cfed90871313e3691ae1db08a2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d",
        "lessThan": "ffbce350c6fd1e99116ea57383b9031717e36d3b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d",
        "lessThan": "98f3de6ef4efbd899348d333f0902dc4ff14380c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d",
        "lessThan": "790304c02bf9bd7b8171feda4294d6e62d32ae8f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d",
        "lessThan": "922d48fe8c19f388ffa2f709f33acaae4e408de2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d",
        "lessThan": "30010c952077a1c89ecdd71fc4d574c75a8f5617",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f2283680a80571ca82d710bc6ecd8f8beac67d63",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6.1.71",
        "lessThan": "6.1.175",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "5.15.145",
        "lessThan": "5.16",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/smb/server/smb2pdu.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "6.6"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "6.6",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.1.175",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.136",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.84",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.25",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.2",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/smb/server/smb2pdu.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-31705

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#28316 · Revision 1
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Publisher date
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