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debiancveDebian Security Bug TrackerDEBIANCVE:CVE-2023-52609
HistoryMar 18, 2024 - 11:15 a.m.

CVE-2023-52609

2024-03-1811:15:07
Debian Security Bug Tracker
security-tracker.debian.org
7
linux
kernel
vulnerability

6.6 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

13.0%

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.

6.6 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

13.0%