CVE-2026-72381 (GCVE-0-2026-72381)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
ksmbd: fix use-after-free of fp->owner.name in durable handle owner check
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free of fp->owner.name in durable handle owner check Two concurrent SMB2 durable reconnects (DH2C/DHnC) on the same persistent_id race the fp->owner.name compare-read in ksmbd_vfs_compare_durable_owner() against the kfree() in ksmbd_reopen_durable_fd()'s reopen-success path. fp->owner.name is a standalone kstrdup() buffer whose lifetime is independent of the fp refcount, and the two sites share no lock: the compare reads the buffer while the reopen frees it, so the strcmp() can dereference freed memory. Commit 7ce4fc40018d ("ksmbd: fix durable reconnect double-bind race in ksmbd_reopen_durable_fd") made the fp->conn claim atomic under global_ft.lock (closing the owner.name double-free and the ksmbd_file write-UAF), but the compare-read versus reopen-free pair was left unserialized. BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80 Read of size 1 by task kworker strcmp ksmbd_vfs_compare_durable_owner smb2_check_durable_oplock smb2_open Freed by task kworker: kfree ksmbd_reopen_durable_fd smb2_open Allocated by task kworker: kstrdup session_fd_check smb2_session_logoff The buggy address belongs to the cache kmalloc-8 Serialize both sides of the race with fp->f_lock. The global durable file-table lock still protects the durable reconnect claim, but fp->owner.name is per-open state and does not need to block unrelated durable table lookups or reconnects. The teardown is left at its existing location after the reopen-success point so that an __open_id() rollback still retains owner.name for a later legitimate reconnect to verify.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 712cdf917e77a6444ce3836874829d770db20ee6 , < fb978d72052704c6b06c6b0f129fcd60b77169f5 (git)
Affected: c7f0f0d01c88bdcb8b1694d7d321670013f7ed7d , < 93d4d46bf9d442a12ea87278049ec416962c627f (git)
Affected: 00ce8d6789dae72d042a4522264964c72891ca37 , < 5a5ac2852cd326529d02f778bc1aa6184701f4d7 (git)
Affected: 49110a8ce654bbe56bef7c5e44cce31f4b102b8a , < ed98719be41389d416953b8ef9f07a07dfea6b2b (git)
Affected: 49110a8ce654bbe56bef7c5e44cce31f4b102b8a , < 38637163501fd9e2f684b8cd275d0db5d79f37c6 (git)
Affected: c908c853f304a4969b5aa10eba0b50350cc65b80 (git)
Affected: 6.6.142 , < 6.6.145 (semver)
Affected: 6.12.92 , < 6.12.97 (semver)
Affected: 6.18.25 , < 6.18.40 (semver)
Affected: 7.0.2 , < 7.1 (semver)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of fp-\u003eowner.name in durable handle owner check\n\nTwo concurrent SMB2 durable reconnects (DH2C/DHnC) on the same\npersistent_id race the fp-\u003eowner.name compare-read in\nksmbd_vfs_compare_durable_owner() against the kfree() in\nksmbd_reopen_durable_fd()\u0027s reopen-success path. fp-\u003eowner.name is a\nstandalone kstrdup() buffer whose lifetime is independent of the fp\nrefcount, and the two sites share no lock: the compare reads the buffer\nwhile the reopen frees it, so the strcmp() can dereference freed memory.\n\nCommit 7ce4fc40018d (\"ksmbd: fix durable reconnect double-bind race in\nksmbd_reopen_durable_fd\") made the fp-\u003econn claim atomic under\nglobal_ft.lock (closing the owner.name double-free and the ksmbd_file\nwrite-UAF), but the compare-read versus reopen-free pair was left\nunserialized.\n\n  BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80\n  Read of size 1 by task kworker\n    strcmp\n    ksmbd_vfs_compare_durable_owner\n    smb2_check_durable_oplock\n    smb2_open\n  Freed by task kworker:\n    kfree\n    ksmbd_reopen_durable_fd\n    smb2_open\n  Allocated by task kworker:\n    kstrdup\n    session_fd_check\n    smb2_session_logoff\n  The buggy address belongs to the cache kmalloc-8\n\nSerialize both sides of the race with fp-\u003ef_lock.  The global durable\nfile-table lock still protects the durable reconnect claim, but\nfp-\u003eowner.name is per-open state and does not need to block unrelated\ndurable table lookups or reconnects.  The teardown is left at its\nexisting location after the reopen-success point so that an __open_id()\nrollback still retains owner.name for a later legitimate reconnect to\nverify."
        }
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            "baseSeverity": "CRITICAL",
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            "version": "3.1"
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              "lang": "en",
              "value": "AV:N - The flaw is reached via ksmbd\u0027s in-kernel SMB2 server on TCP port 445; remote SMB2_CREATE durable-handle reconnect packets (DH2C/DHnC) traverse ksmbd_conn_handler_loop() -\u003e smb2_check_user_session() -\u003e smb2_open() -\u003e parse_durable_handle_context() -\u003e smb2_check_durable_oplock() / ksmbd_reopen_durable_fd().\nAC:L - The attacker controls both sides of the race by opening a durable handle, issuing SMB2_LOGOFF to preserve owner.name via session_fd_check(), then sending concurrent SMB2_CREATE durable reconnect requests for the same persistent_id from multiple connections; no timing or layout outside attacker control is required.\nPR:N - Exploitation requires only network reachability to ksmbd and valid SMB session credentials (guest or any share user) plus tree connect; no elevated host privileges, capabilities, or local access are needed beyond share-level SMB access obtainable through the protocol itself.\nUI:N - No victim user interaction is required beyond a server running ksmbd with durable handles enabled; the attacker programmatically drives the open, logoff, and concurrent reconnect SMB2 sequence over the network.\nS:U - Impact is confined to kernel heap memory corruption and privilege escalation within the same host security authority; this is not a VM escape, container boundary bypass, or IOMMU/DMA isolation break.\nC:H - strcmp() in ksmbd_vfs_compare_durable_owner() dereferences a freed kmalloc-8 fp-\u003eowner.name buffer while a concurrent ksmbd_reopen_durable_fd() kfree() runs; this slab use-after-free enables arbitrary kernel memory disclosure via heap reuse.\nI:H - Use-after-free of the standalone owner.name kstrdup buffer provides kernel heap corruption primitives; with heap grooming the freed slab can be reallocated for arbitrary kernel memory writes and control-flow hijacking.\nA:H - KASAN reports slab-use-after-free in strcmp on the owner.name buffer during concurrent smb2_open durable reconnects; the UAF can trigger kernel oops or panic on ksmbd worker threads and is repeatable by resending concurrent reconnect requests."
            }
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        "dateUpdated": "2026-08-17T05:43:32.020Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "datePublished": "2026-08-15T05:56:13.477Z",
    "dateReserved": "2026-08-09T03:40:39.923Z",
    "dateUpdated": "2026-08-17T05:43:32.020Z",
    "state": "PUBLISHED"
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The global durable\\nfile-table lock still protects the durable reconnect claim, but\\nfp-\u003eowner.name is per-open state and does not need to block unrelated\\ndurable table lookups or reconnects.  The teardown is left at its\\nexisting location after the reopen-success point so that an __open_id()\\nrollback still retains owner.name for a later legitimate reconnect to\\nverify.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/server/vfs_cache.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"712cdf917e77a6444ce3836874829d770db20ee6\",\"lessThan\":\"fb978d72052704c6b06c6b0f129fcd60b77169f5\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c7f0f0d01c88bdcb8b1694d7d321670013f7ed7d\",\"lessThan\":\"93d4d46bf9d442a12ea87278049ec416962c627f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"00ce8d6789dae72d042a4522264964c72891ca37\",\"lessThan\":\"5a5ac2852cd326529d02f778bc1aa6184701f4d7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"49110a8ce654bbe56bef7c5e44cce31f4b102b8a\",\"lessThan\":\"ed98719be41389d416953b8ef9f07a07dfea6b2b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"49110a8ce654bbe56bef7c5e44cce31f4b102b8a\",\"lessThan\":\"38637163501fd9e2f684b8cd275d0db5d79f37c6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c908c853f304a4969b5aa10eba0b50350cc65b80\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6.6.142\",\"lessThan\":\"6.6.145\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.12.92\",\"lessThan\":\"6.12.97\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.18.25\",\"lessThan\":\"6.18.40\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"7.0.2\",\"lessThan\":\"7.1\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/smb/server/vfs_cache.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"7.1\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"7.1\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/38637163501fd9e2f684b8cd275d0db5d79f37c6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5a5ac2852cd326529d02f778bc1aa6184701f4d7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/93d4d46bf9d442a12ea87278049ec416962c627f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ed98719be41389d416953b8ef9f07a07dfea6b2b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/fb978d72052704c6b06c6b0f129fcd60b77169f5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • 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.
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