CVE-2026-90162 (GCVE-0-2026-90162)
Vulnerability from cvelistv5
Published
2026-09-17 16:06
Modified
2026-10-30 12:34
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In 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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/smb/server/smb2pdu.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
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{
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{
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"versionType": "git"
},
{
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{
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"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/smb/server/smb2pdu.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.15"
},
{
"lessThan": "5.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.191",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.191",
"versionStartIncluding": "5.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
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{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.6",
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},
{
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The attacker-controlled data is the SMB2 LOCK request (struct smb2_lock_req lock elements: Offset, Length, Flags) received on TCP/445 by ksmbd_conn_handler_loop(), queued with queue_ksmbd_work(), and dispatched to smb2_lock() via conn-\u003ecmds[SMB2_LOCK_HE]; the racing free is a second SMB2 LOCK with SMB2_LOCKFLAG_UNLOCK on the same FID.\nAC:L - The attacker drives both sides: smb2_lock() publishes a granted ksmbd_lock onto conn-\u003elock_list after vfs_lock_file() succeeds for lock element 0, then a later element in the same LockCount\u003e1 array fails (cmd\u003c0, missing SMB2_LOCKFLAG_MASK, or overlap) and walks rollback_list, while a concurrent SMB2 LOCK UNLOCK on ksmbd-io (WQ_PERCPU) kfree()s that object; the race is retryable.\nPR:L - SMB2_LOCK is not in the smb2_check_user_session() pre-auth skip list (only NEGOTIATE/SESSION_SETUP/ECHO); it requires SMB2_SESSION_VALID, smb2_get_ksmbd_tcon() for a tree id, and ksmbd_lookup_fd_slow() after smb2_open(). An ordinary authenticated share user suffices; this is not a pre-auth handshake.\nUI:N - The attacker completes SESSION_SETUP, TREE_CONNECT and CREATE on their own ksmbd TCP connection, then sends the multi-element SMB2 LOCK and concurrent UNLOCK; no victim mount, click, or administrator action is required.\nS:U - The UAF and double-free of ksmbd_lock and struct file_lock occur in the ksmbd-io worker on the host that accepted the SMB session and do not cross a VM, guest-to-host, or IOMMU/DMA boundary.\nC:H - UNLOCK\u0027s kfree(cmp_lock) leaves rollback reading smb_lock-\u003estart, smb_lock-\u003eend, smb_lock-\u003econn and smb_lock-\u003efl from a freed ksmbd_lock; reclaiming that slab or the associated file_lock_cache object with attacker-controlled contents yields an arbitrary kernel read.\nI:H - The same rollback path list_del()s smb_lock-\u003eflist and smb_lock-\u003eclist on the freed object, then locks_free_lock(smb_lock-\u003efl) and kfree(smb_lock) after UNLOCK already freed both, giving a double-free and list_del write primitive for heap corruption and control-flow hijack.\nA:H - Dereferencing the freed ksmbd_lock (including spin_lock on smb_lock-\u003econn-\u003ellist_lock) and double-freeing ksmbd_lock/file_lock oops or panic the ksmbd-io worker; the LOCK/UNLOCK pair can be repeated to crash the host."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:34:31.271Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/f1371a140722c1d6868f9acf69d601de7d4142bf"
},
{
"url": "https://git.kernel.org/stable/c/b68d4bb6b03a667c305626bd2c242fd162bac17e"
},
{
"url": "https://git.kernel.org/stable/c/65f54ed0289e9a57e6c60b14347ccea4c318f1fc"
},
{
"url": "https://git.kernel.org/stable/c/ff6870cf3b7eccc69d03cbb6f23e3995d96e9a8d"
},
{
"url": "https://git.kernel.org/stable/c/a1d26dfb32919088e3638dca01068df3c4507433"
},
{
"url": "https://git.kernel.org/stable/c/29f74f0f2e6df3b393b7b66e810136d0c64e3c59"
}
],
"title": "ksmbd: defer publishing granted locks to prevent UAF/double-free race",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-90162",
"datePublished": "2026-09-17T16:06:53.136Z",
"dateReserved": "2026-09-11T19:38:34.790Z",
"dateUpdated": "2026-10-30T12:34:31.271Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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