GHSA-7VF5-5XH7-53FM
Vulnerability from github – Published: 2026-10-06 09:31 – Updated: 2026-10-07 09:32In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix use-after-free of iface in cifs_try_adding_channels()
cifs_try_adding_channels() iterates ses->iface_list with list_for_each_entry_safe_from(), which captures the next entry (niface) under iface_lock. The loop body then drops iface_lock for the whole duration of cifs_ses_add_channel().
A concurrent interface refresh (SMB3_request_interfaces() -> parse_server_interfaces()) marks all ifaces inactive and removes and frees any that are not re-advertised via list_del() + kref_put(), where release_iface() is a bare kfree(). Since niface typically has no channel holding a reference, the list reference is its last and it can be freed inside the unlocked window. On continue, the iterator advance step then dereferences niface->iface_head.next, and the loop body reads iface->rdma_capable/is_active, both on freed memory.
Fix this by never keeping an unreferenced list pointer across the unlocked window. Each channel attempt now re-scans the list from the head under iface_lock, takes a kref on the selected candidate, and passes only that referenced candidate to cifs_ses_add_channel(). weight_fulfilled still tracks selection progress, so restarting the scan preserves the original weighted distribution and the weight_fulfilled-before-kref_put ordering on the failure path.
Add a per-pass attempts cap so a flapping interface refresh cannot keep the inner loop spinning within a single tries increment.
{
"affected": [],
"aliases": [
"CVE-2026-98173"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-06T09:17:59Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-after-free of iface in cifs_try_adding_channels()\n\ncifs_try_adding_channels() iterates ses-\u003eiface_list with\nlist_for_each_entry_safe_from(), which captures the next entry\n(niface) under iface_lock. The loop body then drops iface_lock for\nthe whole duration of cifs_ses_add_channel().\n\nA concurrent interface refresh (SMB3_request_interfaces() -\u003e\nparse_server_interfaces()) marks all ifaces inactive and removes and\nfrees any that are not re-advertised via list_del() + kref_put(),\nwhere release_iface() is a bare kfree(). Since niface typically has\nno channel holding a reference, the list reference is its last and it\ncan be freed inside the unlocked window. On continue, the iterator\nadvance step then dereferences niface-\u003eiface_head.next, and the loop\nbody reads iface-\u003erdma_capable/is_active, both on freed memory.\n\nFix this by never keeping an unreferenced list pointer across the\nunlocked window. Each channel attempt now re-scans the list from the\nhead under iface_lock, takes a kref on the selected candidate, and\npasses only that referenced candidate to cifs_ses_add_channel().\nweight_fulfilled still tracks selection progress, so restarting the\nscan preserves the original weighted distribution and the\nweight_fulfilled-before-kref_put ordering on the failure path.\n\nAdd a per-pass attempts cap so a flapping interface refresh cannot\nkeep the inner loop spinning within a single tries increment.",
"id": "GHSA-7vf5-5xh7-53fm",
"modified": "2026-10-07T09:32:12Z",
"published": "2026-10-06T09:31:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98173"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c941f1ebfd26f683de81091473f3596a218abff0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d034e836eefd7ce75e588f7031cffbeec594f5ac"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e99040e5e9c60441e6b4725e1a7b88c3106ae903"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ec36b38e65596950e6c29bed7dfc90b98707c19c"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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