{"id":"CVE-2026-64281","state":"PUBLISHED","title":"svcrdma: wake sq waiters when the transport closes","description":"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() -> svc_delete_xprt() ->\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 ]","publishedAt":"2026-07-25T08:49:24.399Z","updatedAt":"2026-08-17T04:52:36.535Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ccc89b9d1ed233349cfe8d87b842e7351b74d8de","status":"affected","lessThan":"40eedc4253dbda0b29b7961200534dfcecb48ace","versionType":"git"},{"version":"ccc89b9d1ed233349cfe8d87b842e7351b74d8de","status":"affected","lessThan":"e5248a7426030db1e126363f72afdb3b71339a5c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/sunrpc/svc_rdma.h","net/sunrpc/xprtrdma/svc_rdma_recvfrom.c","net/sunrpc/xprtrdma/svc_rdma_rw.c","net/sunrpc/xprtrdma/svc_rdma_sendto.c","net/sunrpc/xprtrdma/svc_rdma_transport.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/sunrpc/svc_rdma.h","net/sunrpc/xprtrdma/svc_rdma_recvfrom.c","net/sunrpc/xprtrdma/svc_rdma_rw.c","net/sunrpc/xprtrdma/svc_rdma_sendto.c","net/sunrpc/xprtrdma/svc_rdma_transport.c"]}],"references":["https://git.kernel.org/stable/c/40eedc4253dbda0b29b7961200534dfcecb48ace","https://git.kernel.org/stable/c/e5248a7426030db1e126363f72afdb3b71339a5c"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64281.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64281","state":"PUBLISHED","datePublished":"2026-07-25T08:49:24.399Z","dateUpdated":"2026-08-17T04:52:36.535Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.777Z"},"containers":{"cna":{"title":"svcrdma: wake sq waiters when the transport closes","descriptions":[{"lang":"en","value":"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() -> svc_delete_xprt() ->\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 ]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ccc89b9d1ed233349cfe8d87b842e7351b74d8de","status":"affected","lessThan":"40eedc4253dbda0b29b7961200534dfcecb48ace","versionType":"git"},{"version":"ccc89b9d1ed233349cfe8d87b842e7351b74d8de","status":"affected","lessThan":"e5248a7426030db1e126363f72afdb3b71339a5c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/sunrpc/svc_rdma.h","net/sunrpc/xprtrdma/svc_rdma_recvfrom.c","net/sunrpc/xprtrdma/svc_rdma_rw.c","net/sunrpc/xprtrdma/svc_rdma_sendto.c","net/sunrpc/xprtrdma/svc_rdma_transport.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/sunrpc/svc_rdma.h","net/sunrpc/xprtrdma/svc_rdma_recvfrom.c","net/sunrpc/xprtrdma/svc_rdma_rw.c","net/sunrpc/xprtrdma/svc_rdma_sendto.c","net/sunrpc/xprtrdma/svc_rdma_transport.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/40eedc4253dbda0b29b7961200534dfcecb48ace"},{"url":"https://git.kernel.org/stable/c/e5248a7426030db1e126363f72afdb3b71339a5c"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - An unauthenticated peer can reach the vulnerable NFS/RDMA server over an IP-based RDMA connection, including routable iWARP or RoCE deployments.\nAC:L - The attacker controls concurrent request batching, Send Queue pressure, and the remote disconnect that strands waiters, and can repeat attempts without relying on an uncontrollable race.\nPR:N - Malformed RPC/RDMA headers can reach svc_rdma_sq_wait() through the transport-error reply path before RPC authentication, NFS export authorization, or credential validation.\nUI:N - Exploitation requires only attacker-generated RDMA traffic and disconnection; no victim action is required after the service is listening.\nS:U - The vulnerable transport and affected NFS service threads belong to the same host kernel security authority.\nC:N - The defect is a missed wake-up that pins references and does not disclose data or provide a memory-read primitive.\nI:N - No memory corruption, unintended write, or data modification occurs; retained references prevent premature object destruction.\nA:H - Waiters remain indefinitely in TASK_UNINTERRUPTIBLE, and an attacker can park all NFS service workers and block transport teardown or server shutdown, causing complete service availability loss."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:52:36.535Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}