GHSA-5GF3-C25P-FM95
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
sunrpc: wait for in-flight TLS handshake callback when cancel loses race
When wait_for_completion_interruptible_timeout() in svc_tcp_handshake() returns 0 (timeout) or -ERESTARTSYS (signal) and tls_handshake_cancel() then returns false, handshake_complete() has won the cancellation race: it has set HANDSHAKE_F_REQ_COMPLETED and is about to invoke svc_tcp_handshake_done(), but the callback's side effects on xpt_flags and on svsk->sk_handshake_done have not yet committed.
The current code reads xpt_flags immediately to decide whether the session succeeded. Two races result.
If the callback has executed set_bit(XPT_TLS_SESSION) but not yet clear_bit(XPT_HANDSHAKE), svc_tcp_handshake() sees a session, enqueues the transport, and returns. svc_xprt_received() then clears XPT_BUSY, a worker thread picks the transport up, the dispatcher in svc_handle_xprt() observes XPT_HANDSHAKE still set, and xpo_handshake is invoked a second time. That svc_tcp_handshake() calls init_completion(&svsk->sk_handshake_done) while the original callback concurrently calls complete_all() on it, corrupting the embedded swait_queue.
If the callback has set HANDSHAKE_F_REQ_COMPLETED but not yet entered svc_tcp_handshake_done(), svc_tcp_handshake() reads XPT_TLS_SESSION as clear and tears the connection down even though the handshake is about to succeed.
Wait for the callback to commit before inspecting xpt_flags. The completion is guaranteed to fire because handshake_complete() invokes svc_tcp_handshake_done() unconditionally once it has set HANDSHAKE_F_REQ_COMPLETED.
{
"affected": [],
"aliases": [
"CVE-2026-72221"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:21:40Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: wait for in-flight TLS handshake callback when cancel loses race\n\nWhen wait_for_completion_interruptible_timeout() in\nsvc_tcp_handshake() returns 0 (timeout) or -ERESTARTSYS (signal) and\ntls_handshake_cancel() then returns false, handshake_complete() has\nwon the cancellation race: it has set HANDSHAKE_F_REQ_COMPLETED and\nis about to invoke svc_tcp_handshake_done(), but the callback\u0027s\nside effects on xpt_flags and on svsk-\u003esk_handshake_done have not\nyet committed.\n\nThe current code reads xpt_flags immediately to decide whether the\nsession succeeded. Two races result.\n\nIf the callback has executed set_bit(XPT_TLS_SESSION) but not yet\nclear_bit(XPT_HANDSHAKE), svc_tcp_handshake() sees a session,\nenqueues the transport, and returns. svc_xprt_received() then\nclears XPT_BUSY, a worker thread picks the transport up, the\ndispatcher in svc_handle_xprt() observes XPT_HANDSHAKE still set,\nand xpo_handshake is invoked a second time. That svc_tcp_handshake()\ncalls init_completion(\u0026svsk-\u003esk_handshake_done) while the original\ncallback concurrently calls complete_all() on it, corrupting the\nembedded swait_queue.\n\nIf the callback has set HANDSHAKE_F_REQ_COMPLETED but not yet\nentered svc_tcp_handshake_done(), svc_tcp_handshake() reads\nXPT_TLS_SESSION as clear and tears the connection down even though\nthe handshake is about to succeed.\n\nWait for the callback to commit before inspecting xpt_flags. The\ncompletion is guaranteed to fire because handshake_complete()\ninvokes svc_tcp_handshake_done() unconditionally once it has set\nHANDSHAKE_F_REQ_COMPLETED.",
"id": "GHSA-5gf3-c25p-fm95",
"modified": "2026-08-17T06:33:17Z",
"published": "2026-08-15T06:32:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72221"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0d8ceb39884148dc7a2fdf71e1cac5961ed1d2b9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/65b23bec1fca6e9ebdc3e6041ebf8c6ab074141b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a4f878e8ecd729ccf2e50993444e217583adeace"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d00e32f84ca1a77cb67a3fbf59f58dada95f5a21"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e0f4691d42a54d359d8b64509fd9ab938d4f2a33"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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