SUNRPC: close backchannel before destroying callback service

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89546
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:37 UTC
Updated2026-09-11 20:19:37 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: SUNRPC: close backchannel before destroying callback service A backchannel receive can complete a request while the NFS callback service is being torn down. xprt_complete_bc_request() removes the request from bc_pa_list, drops bc_alloc_count, marks the request in use, and then asks xprt_enqueue_bc_request() to hand it to the callback service. If teardown has already cleared xprt->bc_serv, xprt_enqueue_bc_request() currently returns without enqueueing or freeing the committed request. The xprt_get() taken on entry is leaked as well. If the producer wins the race before bc_serv is cleared, it can also enqueue onto sv_cb_list after nfs_callback_down() has stopped the callback threads, leaving the request linked to a svc_serv that is about to be freed. Close the producer side before callback threads are stopped. Add xprt_svc_shutdown_bc() to clear xprt->bc_serv under bc_pa_lock, and call it on callback shutdown and callback-start failure before stopping the service threads. Requests that lose the NULL transition in xprt_enqueue_bc_request() are released through the normal backchannel free path after balancing bc_slot_count. Finally, drain any remaining sv_cb_list requests after the callback threads have stopped and before svc_destroy() frees the service.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 441244d4273a8037b265fd254dfdaca5fa736ee2 6debde9e3e6ae21dcca75837b4247b13ca4ea2b8 git Not specified
CNA Linux Linux affected 441244d4273a8037b265fd254dfdaca5fa736ee2 3674f780f47d2906b5a0f7199b66973067bdfeca git Not specified
CNA Linux Linux affected 6.19 Not specified
CNA Linux Linux unaffected 6.19 semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/3674f780f47d2906b5a0f7199b66973067bdfeca 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6debde9e3e6ae21dcca75837b4247b13ca4ea2b8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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