CVE-2026-53394

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.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

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