In 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.
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.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 12 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-911 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 11 Sep 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In 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. | |
| Title | SUNRPC: close backchannel before destroying callback service | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-11T19:44:21.898Z
Reserved: 2026-09-11T19:38:34.722Z
Link: CVE-2026-89546
No data.
Status : Received
Published: 2026-09-11T20:19:37.960
Modified: 2026-09-11T20:19:37.960
Link: CVE-2026-89546
OpenCVE Enrichment
No data.
Weaknesses