GHSA-X2QC-QFQC-6VMR
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-18 18:31In the Linux kernel, the following vulnerability has been resolved:
ksmbd: defer publishing granted locks to prevent UAF/double-free race
In smb2_lock(), mid-batch granted locks are published to connection-wide (conn->lock_list) and file-wide (fp->lock_list) lists immediately upon vfs_lock_file() success, while also remaining tracked on the stack-local rollback_list.
If a subsequent element in the same SMB2_LOCK request array fails validation or execution, the thread jumps to out: and walks rollback_list to undo previously granted locks. However, because the granted lock was already published to conn->lock_list, a concurrent UNLOCK request on the same connection can find the lock object and kfree() it before the rollback loop executes.
When the granting thread subsequently walks rollback_list, it dereferences and frees the already-freed ksmbd_lock structure, resulting in a Use-After-Free and Double-Free (on both ksmbd_lock and struct file_lock).
Fix this by deferring the publication of granted locks to conn->lock_list and fp->lock_list until after the entire array of lock elements has been processed without error. Mid-batch grants remain tracked exclusively on the request-local rollback_list until the whole batch succeeds, eliminating the race window.
{
"affected": [],
"aliases": [
"CVE-2026-90162"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:09Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: defer publishing granted locks to prevent UAF/double-free race\n\nIn smb2_lock(), mid-batch granted locks are published to connection-wide\n(conn-\u003elock_list) and file-wide (fp-\u003elock_list) lists immediately upon\nvfs_lock_file() success, while also remaining tracked on the stack-local\nrollback_list.\n\nIf a subsequent element in the same SMB2_LOCK request array fails\nvalidation or execution, the thread jumps to out: and walks\nrollback_list to undo previously granted locks. However, because the\ngranted lock was already published to conn-\u003elock_list, a concurrent\nUNLOCK request on the same connection can find the lock object and\nkfree() it before the rollback loop executes.\n\nWhen the granting thread subsequently walks rollback_list, it\ndereferences and frees the already-freed ksmbd_lock structure, resulting\nin a Use-After-Free and Double-Free (on both ksmbd_lock and struct\nfile_lock).\n\nFix this by deferring the publication of granted locks to\nconn-\u003elock_list and fp-\u003elock_list until after the entire array of lock\nelements has been processed without error. Mid-batch grants remain\ntracked exclusively on the request-local rollback_list until the whole\nbatch succeeds, eliminating the race window.",
"id": "GHSA-x2qc-qfqc-6vmr",
"modified": "2026-09-18T18:31:27Z",
"published": "2026-09-17T18:31:53Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90162"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/29f74f0f2e6df3b393b7b66e810136d0c64e3c59"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a1d26dfb32919088e3638dca01068df3c4507433"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- 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.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.