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ksmbd: fix use-after-free in oplock break notification

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in oplock break notification smb2_oplock_break_noti() reads opinfo->conn without any lock and dereferences it after two allocations which may sleep. When the durable handle owning the oplock is disconnected, session_fd_check() clears opinfo->conn and drops its conn reference under ci->m_lock, and the last ksmbd_conn_put() frees the connection. A break triggered by another connection that races with the teardown can then resurrect the freed connection: ksmbd_conn_get() is a plain atomic_inc, and the queued break work later dereferences the stale conn via ksmbd_conn_write(), a use-after-free reachable by any authenticated client holding a durable batch oplock. Thread the caller's inode into the notification path instead of taking a new reference on it. Every caller of oplock_break() already holds a live ksmbd_file (or an explicit ksmbd_inode_lookup_lock() reference, in the parent lease break paths) on the inode that owns the break target's oplock list, so ci cannot be freed during the call, and its lock can be taken without dereferencing opinfo->o_fp, which a concurrent close may free. Select and pin the connection under ci->m_lock, the same lock session_fd_check() and ksmbd_reopen_durable_fd() use to update opinfo->conn, so a concurrent detach either loses the race to the clear or keeps the connection alive until the notification work releases it. Transfer the reference to the work it

Announced Source revision 1
Original source ↗

CVE-2026-80926

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-2026-80926

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": "945a86b21b40fb17183f5b27461baa6f03e2467f",
        "lessThan": "892f643b141aee3f7aa7c0fc61ddcb55c59f1996",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1ff58dcfcab434ebb51649da33774fbb8e1f7b67",
        "lessThan": "5de0527f782430b1109a447646e32033ad018a6a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e735dbd489e3ea02be78dba991056fe1138be51e",
        "lessThan": "c8279ae8df68cce9cd3b785e85f7a86c80a46e78",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "b003086d76968298f22e7cf62239833b5a3a06b1",
        "lessThan": "8cc98db4fc590e6c7d9db6529320982ee16c5d1d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "b003086d76968298f22e7cf62239833b5a3a06b1",
        "lessThan": "0e753899627b5e28a9fea8bca98262a6f65a2452",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75e33deda658c1ab3a9336cbdb1436536f9b3660",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6.6.143",
        "lessThan": "6.6.158",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.12.94",
        "lessThan": "6.12.111",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.18.36",
        "lessThan": "6.18.51",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "7.0.13",
        "lessThan": "7.1",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/smb/server/oplock.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "7.1"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "7.1",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.51",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.5",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/smb/server/oplock.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-80926

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#34887 · Revision 1
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Publisher date
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