ksmbd: fix tree connection use-after-free in smb2_tree_connect()
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix tree connection use-after-free in smb2_tree_connect() ksmbd_tree_conn_connect() publishes a new tree connection in sess->tree_conns with a single reference and returns its pointer to smb2_tree_connect(). The handler continues to initialize the object and build the response after publication. A concurrent session logoff can erase the connection and drop that reference, freeing the object while the handler still uses it. BUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90 smb2_tree_connect (fs/smb/server/smb2pdu.c:2872) handle_ksmbd_work process_one_work worker_thread kthread After xa_store() succeeds, take a second reference before releasing tree_conns_lock. The original reference belongs to the xarray entry and the second belongs to the creating smb2_tree_connect() handler. Keep the references balanced in every path: - On normal exit or an error after publication, smb2_tree_connect() drops its creator reference. Error cleanup also calls ksmbd_tree_conn_disconnect(), which drops the xarray reference only if it removes the exact entry. - SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop its xarray reference. The request's existing lookup reference remains owned by the request and is released by the existing cleanup. - Session LOGOFF removes each entry and drops its xarray reference. If it wins the race, later cleanup sees that the entry is gone and does not drop that
CVE-2026-89788
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-2026-89788
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": "33b235a6e6ebe0f05f3586a71e8d281d00f71e2e",
"lessThan": "ca3a3984bf445aaec69f6937f11e560d4b849365",
"versionType": "git"
},
{
"status": "affected",
"version": "33b235a6e6ebe0f05f3586a71e8d281d00f71e2e",
"lessThan": "bd58a52738f7576ee5f5eb74243df13f902c8051",
"versionType": "git"
},
{
"status": "affected",
"version": "33b235a6e6ebe0f05f3586a71e8d281d00f71e2e",
"lessThan": "4e30fbd26e84efa2e5cbec4eb11e126ac0c79313",
"versionType": "git"
},
{
"status": "affected",
"version": "33b235a6e6ebe0f05f3586a71e8d281d00f71e2e",
"lessThan": "b5ec6c462aab1062cf5d1e667ba7c6442f737055",
"versionType": "git"
},
{
"status": "affected",
"version": "dd45db4d9bbc8f122a9b4db5ce94ae29fcf03d3c",
"versionType": "git"
},
{
"status": "affected",
"version": "7b58ee8d0b91359554cf219cd4f33872ea2afd66",
"versionType": "git"
},
{
"status": "affected",
"version": "5.15.145",
"lessThan": "5.16",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.1.71",
"lessThan": "6.2",
"versionType": "semver"
}
],
"programFiles": [
"fs/smb/server/mgmt/tree_connect.c",
"fs/smb/server/smb2pdu.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.6"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.6",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/smb/server/mgmt/tree_connect.c",
"fs/smb/server/smb2pdu.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89788
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #46725 · Revision 1
- Added to Heist Feed
- Publisher date