CVE-2023-52609: Debian Linux

Medium severity, CVSS 4.7. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: binder: fix race between mmput() and do_exit() Task A calls binder_update_page_range() to allocate and insert pages on a remote address space from Task B. For this, Task A pins the remote mm via mmget_not_zero() first. This can race with Task B do_exit() and the final mmput() refcount decrement will come from Task A. Task A | Task B ------------------+------------------ mmget_not_zero() | | do_exit() | exit_mm() | mmput() mmput() | exit_mmap() | remove_vma() | fput() | In this case, the work of ____fput() from Task B is queued up in Task A as TWA_RESUME. So in theory, Task A returns to userspace and the cleanup work gets executed. However, Task A instead sleep, waiting for a reply from Task B that never comes (it's dead). This means the binder_deferred_release() is blocked until an unrelated binder event forces Task A to go back to userspace. All the associated death notifications will also be delayed until then. In order to fix this use mmput_async() that will schedule the work in the corresponding mm->async_put_work WQ instead of Task A.

Affected products

• Debian Debian Linux: version 10.0 only
• Linux Linux Kernel: from 2.6.29, before 4.19.306 (fixed in 4.19.306); from 4.20, before 5.4.268 (fixed in 5.4.268); from 5.5, before 5.10.209 (fixed in 5.10.209); from 5.11, before 5.15.148 (fixed in 5.15.148); from 5.16, before 6.1.75 (fixed in 6.1.75); from 6.2, before 6.6.14 (fixed in 6.6.14); …

Published 2024-03-18. Last modified 2026-06-17.