CVE-2026-53394nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race

Official description

In the Linux kernel, the following vulnerability has been resolved: nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race When find_or_alloc_open_stateowner() encounters an unconfirmed owner, it calls release_openowner() and sets oo = NULL. Control then falls through past the `if (oo)` guard -- which would have freed any pre-allocated `new` -- and unconditionally executes `new = alloc_stateowner(...)`. If `new` was already allocated on a prior iteration, the pointer is silently overwritten and the previous allocation (slab object + owner name buffer) is leaked. This requires a race: two NFSv4.0 OPEN threads with the same owner string, where a concurrent thread inserts a new unconfirmed owner into the hash between retry iterations. The window is narrow but repeatable under adversarial conditions. Fix by adding `goto retry` after `oo = NULL` so the already-allocated `new` is reused on the next iteration rather than overwritten.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/c9aefb2b5f11337c9202c5bd0c45d71198449718
• https://git.kernel.org/stable/c/017a6150106b054cc84d1b0582d97bd3a74d4281
• https://git.kernel.org/stable/c/a10bf67fe06469a71a401f72f328237345d553c0
• https://git.kernel.org/stable/c/57aee7a35bb12753057c5b65d72d1f46c0e95b07