CVE-2024-42152

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

nvmet: fix a possible leak when destroy a ctrl during qp establishment

In nvmet_sq_destroy we capture sq->ctrl early and if it is non-NULL we know that a ctrl was allocated (in the admin connect request handler) and we need to release pending AERs, clear ctrl->sqs and sq->ctrl (for nvme-loop primarily), and drop the final reference on the ctrl.

However, a small window is possible where nvmet_sq_destroy starts (as a result of the client giving up and disconnecting) concurrently with the nvme admin connect cmd (which may be in an early stage). But before kill_and_confirm of sq->ref (i.e. the admin connect managed to get an sq live reference). In this case, sq->ctrl was allocated however after it was captured in a local variable in nvmet_sq_destroy. This prevented the final reference drop on the ctrl.

Solve this by re-capturing the sq->ctrl after all inflight request has completed, where for sure sq->ctrl reference is final, and move forward based on that.

This issue was observed in an environment with many hosts connecting multiple ctrls simoutanuosly, creating a delay in allocating a ctrl leading up to this race window.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

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/2f3c22b1d3d7e86712253244797a651998c141fa
• https://git.kernel.org/stable/c/5502c1f1d0d7472706cc1f201aecf1c935d302d1
• https://git.kernel.org/stable/c/818004f2a380420c19872171be716174d4985e33
• https://git.kernel.org/stable/c/940a71f08ef153ef807f751310b0648d1fa5d0da
• https://git.kernel.org/stable/c/b4fed1443a6571d49c6ffe7d97af3bbe5ee6dff5
• https://git.kernel.org/stable/c/c758b77d4a0a0ed3a1292b3fd7a2aeccd1a169a4