GHSA-XXJX-GF9Q-559X
Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30In the Linux kernel, the following vulnerability has been resolved:
svcrdma: wake sq waiters when the transport closes
Threads parked in svc_rdma_sq_wait() on sc_sq_ticket_wait or sc_send_wait can hang indefinitely in TASK_UNINTERRUPTIBLE state across transport teardown, pinning svc_xprt references and blocking svc_rdma_free().
The close path sets XPT_CLOSE before invoking xpo_detach and both wait_event predicates include an XPT_CLOSE term, but the predicates are re-evaluated only on wakeup. sc_sq_ticket_wait has no completion-driven wake path; it is advanced solely by the chained ticket handoff inside svc_rdma_sq_wait() itself. Without an explicit wake at close, parked threads never observe XPT_CLOSE, hold their svc_xprt_get reference forever, and svc_rdma_free() blocks on xpt_ref dropping to zero.
Two close entry points reach this transport. Local teardown runs svc_rdma_detach() from svc_handle_xprt() -> svc_delete_xprt() -> xpo_detach() on a worker thread. A remote disconnect arrives at svc_rdma_cma_handler(), which calls svc_xprt_deferred_close(): that sets XPT_CLOSE and enqueues the transport but does not access either RDMA waitqueue, so a worker already parked in svc_rdma_sq_wait() never re-evaluates its predicate. With every worker parked on this transport, no thread is available to run the local teardown either, and the wake site there is unreachable.
Introduce svc_rdma_xprt_deferred_close(), a thin svcrdma wrapper that calls svc_xprt_deferred_close() and then wakes both sc_sq_ticket_wait and sc_send_wait. Convert the svcrdma producers that called svc_xprt_deferred_close() directly: svc_rdma_cma_handler(), qp_event_handler(), svc_rdma_post_send_err(), svc_rdma_wc_send(), the sendto drop path, the rw completion error paths, and the recvfrom flush and read-list error paths.
Wake both waitqueues from svc_rdma_detach() as well. The synchronous svc_xprt_close() path (backchannel ENOTCONN, device removal via svc_rdma_xprt_done) reaches detach without flowing through svc_xprt_deferred_close() and therefore does not invoke the new helper.
[ cel: add svc_rdma_xprt_deferred_close() to complete the fix ]
{
"affected": [],
"aliases": [
"CVE-2026-64281"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-25T10:17:08Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: wake sq waiters when the transport closes\n\nThreads parked in svc_rdma_sq_wait() on sc_sq_ticket_wait or\nsc_send_wait can hang indefinitely in TASK_UNINTERRUPTIBLE state\nacross transport teardown, pinning svc_xprt references and\nblocking svc_rdma_free().\n\nThe close path sets XPT_CLOSE before invoking xpo_detach and both\nwait_event predicates include an XPT_CLOSE term, but the\npredicates are re-evaluated only on wakeup. sc_sq_ticket_wait has\nno completion-driven wake path; it is advanced solely by the\nchained ticket handoff inside svc_rdma_sq_wait() itself. Without\nan explicit wake at close, parked threads never observe\nXPT_CLOSE, hold their svc_xprt_get reference forever, and\nsvc_rdma_free() blocks on xpt_ref dropping to zero.\n\nTwo close entry points reach this transport. Local teardown runs\nsvc_rdma_detach() from svc_handle_xprt() -\u003e svc_delete_xprt() -\u003e\nxpo_detach() on a worker thread. A remote disconnect arrives at\nsvc_rdma_cma_handler(), which calls svc_xprt_deferred_close():\nthat sets XPT_CLOSE and enqueues the transport but does not\naccess either RDMA waitqueue, so a worker already parked in\nsvc_rdma_sq_wait() never re-evaluates its predicate. With every\nworker parked on this transport, no thread is available to run\nthe local teardown either, and the wake site there is\nunreachable.\n\nIntroduce svc_rdma_xprt_deferred_close(), a thin svcrdma wrapper\nthat calls svc_xprt_deferred_close() and then wakes both\nsc_sq_ticket_wait and sc_send_wait. Convert the svcrdma producers\nthat called svc_xprt_deferred_close() directly:\nsvc_rdma_cma_handler(), qp_event_handler(),\nsvc_rdma_post_send_err(), svc_rdma_wc_send(), the sendto drop\npath, the rw completion error paths, and the recvfrom flush and\nread-list error paths.\n\nWake both waitqueues from svc_rdma_detach() as well. The\nsynchronous svc_xprt_close() path (backchannel ENOTCONN, device\nremoval via svc_rdma_xprt_done) reaches detach without flowing\nthrough svc_xprt_deferred_close() and therefore does not invoke\nthe new helper.\n\n[ cel: add svc_rdma_xprt_deferred_close() to complete the fix ]",
"id": "GHSA-xxjx-gf9q-559x",
"modified": "2026-07-27T06:30:31Z",
"published": "2026-07-25T12:31:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64281"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/40eedc4253dbda0b29b7961200534dfcecb48ace"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e5248a7426030db1e126363f72afdb3b71339a5c"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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