CVE-2026-89798

Published Sep 16, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: rpcrdma: arm rn_done before publishing the notification rpcrdma_rn_register() inserts @rn into rd_xa with xa_alloc() before storing the caller's callback in rn->rn_done. The xarray makes @rn reachable to rpcrdma_remove_one(), which walks rd_xa and invokes rn->rn_done(rn) for every registered notification. A device removal that races a fresh registration can therefore observe @rn with rn_done still NULL, because the notification objects are zero allocated by their owners, and call through a NULL function pointer. Store rn->rn_done before xa_alloc() publishes @rn. The xarray's store-side and load-side ordering then guarantees that any CPU which finds @rn in rd_xa also observes the armed callback. rpcrdma_rn_unregister() treats a non-NULL rn_done as the sentinel for a completed registration, so the early store must not survive a failed registration. Clear rn_done again when xa_alloc() fails. Were it left set, the failed-accept cleanup path would call rpcrdma_rn_unregister() on an @rn that was never inserted, erasing an unrelated rd_xa slot and underflowing rd_kref.

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References

Frequently Asked Questions

What is CVE-2026-89798? +
In the Linux kernel, the following vulnerability has been resolved: rpcrdma: arm rn_done before publishing the notification rpcrdma_rn_register() inserts @rn into rd_xa with xa_alloc() before storing the caller's callback in rn->rn_done. The xarray makes @rn reachable to rpcrdma_remove_one(), which walks rd_xa and invokes rn->rn_done(rn) for every registered notification. A device removal that races a fresh registration can therefore observe @rn with rn_done still NULL, because the notification objects are zero allocated by their owners, and call through a NULL function pointer. Store rn->rn_done before xa_alloc() publishes @rn. The xarray's store-side and load-side ordering then guarantees that any CPU which finds @rn in rd_xa also observes the armed callback. rpcrdma_rn_unregister() treats a non-NULL rn_done as the sentinel for a completed registration, so the early store must not survive a failed registration. Clear rn_done again when xa_alloc() fails. Were it left set, the failed-accept cleanup path would call rpcrdma_rn_unregister() on an @rn that was never inserted, erasing an unrelated rd_xa slot and underflowing rd_kref.
How do I check if I'm vulnerable to CVE-2026-89798? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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