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medium4.7

CVE-2023-52609

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 a…

Impact

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

VendorProductAffected versions
LinuxLinux Kernel
from 2.6.29 before 4.19.306
from 4.20 before 5.4.268
from 5.5 before 5.10.209
from 5.11 before 5.15.148
from 5.16 before 6.1.75
from 6.2 before 6.6.14
DebianDebian Linux
Version 10.0

Weakness classification

CWE-362

References