CVE-2026-98533 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
ipe: protect the dm-verity root hash with RCU
ipe_bdev_setintegrity() frees the old root hash when dm-verity publishes a new one on ->preresume, while policy evaluation can still be dereferencing it.
Protect the root hash with RCU. The evaluation path already runs under rcu_read_lock().
[FW: remove model name according to latest guideline]
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/18/2026
The Linux kernel Integrity Policy Enforcement (IPE) subsystem manages security policies that determine which binaries are allowed to execute on a system, serving as a critical component for enforcing mandatory access control and preventing unauthorized code execution. A significant concurrency flaw was identified within the IPE implementation regarding how it handles updates to the dm-verity root hash during device resumption operations. Specifically, the function ipe_bdev_setintegrity is responsible for updating integrity data when a new root hash is published by dm-verity on the preresume callback path. In this process, the subsystem frees the memory associated with the old root hash before ensuring that all concurrent policy evaluations have completed their access to that data structure.
This race condition arises because the policy evaluation mechanism operates asynchronously and may still be dereferencing pointers to the old root hash at the exact moment it is deallocated by the update routine. Although the evaluation path already runs under an rcu_read_lock context, which typically protects against use-after-free scenarios in read-mostly data structures, the specific implementation failed to properly synchronize the memory reclamation with the grace period required for RCU readers. Consequently, if a policy evaluation thread accesses the root hash after it has been freed but before the RCU grace period expires, it results in a use-after-free vulnerability. This type of flaw is classified under CWE-416, which describes using an invalid pointer following memory reallocation or deallocation, and represents a classic concurrency bug where synchronization primitives are either missing or incorrectly applied to protect shared state during updates.
The operational impact of this vulnerability can range from kernel panics leading to system instability and denial of service to more severe security implications depending on the attacker's capabilities. If an unprivileged user or a compromised process can trigger the dm-verity resumption sequence while policy evaluations are ongoing, they may induce a crash by causing invalid memory accesses within the kernel space. In scenarios where specific heap layout conditions are met, such use-after-free bugs can potentially be exploited to achieve arbitrary code execution with kernel privileges, thereby bypassing all integrity enforcement mechanisms and allowing full control over the operating system. This undermines the fundamental security guarantees provided by dm-verity and IPE, which rely on consistent and atomic updates to maintain trust in the boot chain and runtime binary verification processes.
To mitigate this vulnerability, it is essential that systems apply the upstream kernel patches that correct the synchronization logic within the ipe_bdev_setintegrity function. The fix involves ensuring that the old root hash is not freed until all RCU read-side critical sections have completed their execution, typically by utilizing kfree_rcu or similar mechanisms that defer memory reclamation to a safe point in time after the grace period has passed. Administrators should verify that their Linux kernel versions are updated to include this specific fix for the IPE subsystem. Additionally, organizations relying on dm-verity and integrity enforcement policies should ensure that their deployment pipelines regularly update kernels to patch such concurrency issues, as these low-level synchronization errors can have catastrophic consequences for system security posture. Regular auditing of kernel configurations against known vulnerability databases like CVE details is recommended to maintain resilience against similar race conditions in other subsystems.