CVE-2026-31444 (GCVE-0-2026-31444)
Vulnerability from cvelistv5
Published
2026-04-22 13:53
Modified
2026-04-27 14:03
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
smb_grant_oplock() has two issues in the oplock publication sequence:
1) opinfo is linked into ci->m_op_list (via opinfo_add) before
add_lease_global_list() is called. If add_lease_global_list()
fails (kmalloc returns NULL), the error path frees the opinfo
via __free_opinfo() while it is still linked in ci->m_op_list.
Concurrent m_op_list readers (opinfo_get_list, or direct iteration
in smb_break_all_levII_oplock) dereference the freed node.
2) opinfo->o_fp is assigned after add_lease_global_list() publishes
the opinfo on the global lease list. A concurrent
find_same_lease_key() can walk the lease list and dereference
opinfo->o_fp->f_ci while o_fp is still NULL.
Fix by restructuring the publication sequence to eliminate post-publish
failure:
- Set opinfo->o_fp before any list publication (fixes NULL deref).
- Preallocate lease_table via alloc_lease_table() before opinfo_add()
so add_lease_global_list() becomes infallible after publication.
- Keep the original m_op_list publication order (opinfo_add before
lease list) so concurrent opens via same_client_has_lease() and
opinfo_get_list() still see the in-flight grant.
- Use opinfo_put() instead of __free_opinfo() on err_out so that
the RCU-deferred free path is used.
This also requires splitting add_lease_global_list() to take a
preallocated lease_table and changing its return type from int to void,
since it can no longer fail.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/smb/server/oplock.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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"versionType": "git"
},
{
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"versionType": "git"
},
{
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"status": "affected",
"version": "1d6abf145615dbfe267ce3b0a271f95e3780e18e",
"versionType": "git"
},
{
"lessThan": "6d7e5a918c1d0aad06db0e17677b66fc9a471021",
"status": "affected",
"version": "ce8507ee82c888126d8e7565e27c016308d24cde",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
}
]
},
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/smb/server/oplock.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "6.6.131",
"status": "affected",
"version": "6.6.130",
"versionType": "semver"
},
{
"lessThan": "6.12.80",
"status": "affected",
"version": "6.12.78",
"versionType": "semver"
},
{
"lessThan": "6.18.21",
"status": "affected",
"version": "6.18.19",
"versionType": "semver"
},
{
"lessThan": "6.19.11",
"status": "affected",
"version": "6.19.9",
"versionType": "semver"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
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"cpeMatch": [
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"versionEndExcluding": "6.6.131",
"versionStartIncluding": "6.6.130",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.80",
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"vulnerable": true
},
{
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"vulnerable": true
},
{
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"versionEndExcluding": "6.19.11",
"versionStartIncluding": "6.19.9",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free and NULL deref in smb_grant_oplock()\n\nsmb_grant_oplock() has two issues in the oplock publication sequence:\n\n1) opinfo is linked into ci-\u003em_op_list (via opinfo_add) before\n add_lease_global_list() is called. If add_lease_global_list()\n fails (kmalloc returns NULL), the error path frees the opinfo\n via __free_opinfo() while it is still linked in ci-\u003em_op_list.\n Concurrent m_op_list readers (opinfo_get_list, or direct iteration\n in smb_break_all_levII_oplock) dereference the freed node.\n\n2) opinfo-\u003eo_fp is assigned after add_lease_global_list() publishes\n the opinfo on the global lease list. A concurrent\n find_same_lease_key() can walk the lease list and dereference\n opinfo-\u003eo_fp-\u003ef_ci while o_fp is still NULL.\n\nFix by restructuring the publication sequence to eliminate post-publish\nfailure:\n\n- Set opinfo-\u003eo_fp before any list publication (fixes NULL deref).\n- Preallocate lease_table via alloc_lease_table() before opinfo_add()\n so add_lease_global_list() becomes infallible after publication.\n- Keep the original m_op_list publication order (opinfo_add before\n lease list) so concurrent opens via same_client_has_lease() and\n opinfo_get_list() still see the in-flight grant.\n- Use opinfo_put() instead of __free_opinfo() on err_out so that\n the RCU-deferred free path is used.\n\nThis also requires splitting add_lease_global_list() to take a\npreallocated lease_table and changing its return type from int to void,\nsince it can no longer fail."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-04-27T14:03:10.086Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/9e785f004cbc56390479b77375726ea9b0d1a8a6"
},
{
"url": "https://git.kernel.org/stable/c/7de55bba69cbf0f9280daaea385daf08bc076121"
},
{
"url": "https://git.kernel.org/stable/c/a5c6f6d6ceefed2d5210ee420fb75f8362461f46"
},
{
"url": "https://git.kernel.org/stable/c/6d7e5a918c1d0aad06db0e17677b66fc9a471021"
},
{
"url": "https://git.kernel.org/stable/c/48623ec358c1c600fa1e38368746f933e0f1a617"
}
],
"title": "ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-31444",
"datePublished": "2026-04-22T13:53:41.351Z",
"dateReserved": "2026-03-09T15:48:24.090Z",
"dateUpdated": "2026-04-27T14:03:10.086Z",
"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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