CVE-2022-49939

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

binder: fix UAF of ref->proc caused by race condition

A transaction of type BINDER_TYPE_WEAK_HANDLE can fail to increment the

reference for a node. In this case, the target proc normally releases

the failed reference upon close as expected. However, if the target is

dying in parallel the call will race with binder_deferred_release(), so

the target could have released all of its references by now leaving the

cleanup of the new failed reference unhandled.

The transaction then ends and the target proc gets released making the

ref->proc now a dangling pointer. Later on, ref->node is closed and we

attempt to take spin_lock(&ref->proc->inner_lock), which leads to the

use-after-free bug reported below. Let's fix this by cleaning up the

failed reference on the spot instead of relying on the target to do so.

==================================================================

BUG: KASAN: use-after-free in _raw_spin_lock+0

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References