CVE-2025-21853

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> bpf: avoid holding freeze_mutex during mmap operation<br /> <br /> We use map-&gt;freeze_mutex to prevent races between map_freeze() and<br /> memory mapping BPF map contents with writable permissions. The way we<br /> naively do this means we&amp;#39;ll hold freeze_mutex for entire duration of all<br /> the mm and VMA manipulations, which is completely unnecessary. This can<br /> potentially also lead to deadlocks, as reported by syzbot in [0].<br /> <br /> So, instead, hold freeze_mutex only during writeability checks, bump<br /> (proactively) "write active" count for the map, unlock the mutex and<br /> proceed with mmap logic. And only if something went wrong during mmap<br /> logic, then undo that "write active" counter increment.<br /> <br /> [0] https://lore.kernel.org/bpf/678dcbc9.050a0220.303755.0066.GAE@google.com/