UBUNTU-CVE-2026-93267: Use After Free

In the Linux kernel, the following vulnerability has been resolved: RDMA/core: Fix potential use after free in uverbsfreedmah() When accessing a dmah via the netlink path the only synchronization mechanism for the said dmah is rdmarestrackget(). Currently, rdmarestrackdel() is invoked at the end of uverbsfreedmah(), which is too late, since by that point vendor-specific resources associated with the dmah might already be freed. This can leave a short window where the dmah remains accessible through restrack, leading to a potential use-after-free. Fix this by moving the rdmarestrackbegindel() call to the start of uverbsfreedmah(), ensuring that the dmah is removed from restrack before its internal resources are released. This guarantees that no new users hold references to a dmah that is in the process of destruction. In addition, this change preserves the intended inverted order between create and destroy routines: resources are added to restrack at the end of successful creation, and hence shall be removed from the restrack first thing during the destruction flow, which keeps the lifecycle management consistent and predictable.