CVE-2026-46042

In the Linux kernel, the following vulnerability has been resolved:

mm/mempolicy: fix memory leaks in weighted_interleave_auto_store()

weighted_interleave_auto_store() fetches old_wi_state inside the if (!input) block only. This causes two memory leaks:

1. When a user writes false and the current mode is already manual, the function returns early without freeing the freshly allocated new_wi_state.

2. When a user writes true, old_wi_state stays NULL because the fetch is skipped entirely. The old state is then overwritten by rcu_assign_pointer() but never freed, since the cleanup path is gated on old_wi_state being non-NULL. A user can trigger this repeatedly by writing 1 in a loop.

Fix both leaks by moving the old_wi_state fetch before the input check, making it unconditional. This also allows a unified early return for both true and false when the requested mode matches the current mode.

Reviewed by: Donet Tom donettom@linux.ibm.com

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/39caa9ca863f96b3d00447c5aa200cabda489856
• https://git.kernel.org/stable/c/6fae274ce0e3109cbbc4c18b354eaace1f0af7d7
• https://git.kernel.org/stable/c/c42a7efb9060d89b72708ffaf255d0002c2164a7