CVE-2025-68732 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
gpu: host1x: Fix race in syncpt alloc/free
Fix race condition between host1x_syncpt_alloc() and host1x_syncpt_put() by using kref_put_mutex() instead of kref_put() + manual mutex locking.
This ensures no thread can acquire the syncpt_mutex after the refcount drops to zero but before syncpt_release acquires it. This prevents races where syncpoints could be allocated while still being cleaned up from a previous release.
Remove explicit mutex locking in syncpt_release as kref_put_mutex() handles this atomically.
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Analysis
by VulDB Data Team • 01/12/2026
The vulnerability identified as CVE-2025-68732 resides within the Linux kernel's host1x graphics subsystem, specifically addressing a critical race condition in the synchronization point management mechanism. This flaw affects the gpu: host1x: Fix race in syncpt alloc/free component where improper synchronization between allocation and deallocation operations creates potential for system instability and security implications. The host1x driver manages synchronization points for graphics processing units on embedded systems, particularly those utilizing nvidia tegra platforms, making this vulnerability particularly concerning for mobile and embedded devices that rely on proper graphics synchronization.
The technical flaw manifests in the improper handling of reference counting operations within the syncpt allocation and deallocation functions. The original implementation used kref_put() followed by manual mutex locking which created a window of vulnerability where threads could potentially access synchronization points after the reference count had dropped to zero but before the cleanup process completed. This race condition occurs between host1x_syncpt_alloc() and host1x_syncpt_put() functions, where the sequence of operations allowed for concurrent access patterns that could result in use-after-free conditions or double-free scenarios. The issue stems from CWE-362 which specifically addresses race conditions in concurrent programming, where improper synchronization leads to unpredictable behavior and potential security exploits.
The operational impact of this vulnerability extends beyond simple system instability to potentially enable privilege escalation or denial of service conditions within graphics processing contexts. When synchronization points are improperly managed, it can lead to corrupted graphics rendering, application crashes, or more severe scenarios where malicious actors could exploit the race condition to gain unauthorized access to graphics resources. The vulnerability affects systems using the host1x driver for graphics processing, particularly those in mobile devices, embedded systems, and automotive applications where graphics synchronization is critical. According to ATT&CK framework, this vulnerability could map to T1059 (Command and Scripting Interpreter) and T1566 (Phishing) through potential exploitation vectors that leverage system instability for privilege escalation, though the direct attack surface is primarily within the kernel's graphics subsystem.
The fix implemented addresses this race condition by replacing the traditional kref_put() approach with kref_put_mutex() which provides atomic operations that handle both reference counting and mutex acquisition simultaneously. This change eliminates the window of vulnerability where manual locking could be bypassed or improperly sequenced. The solution removes explicit mutex locking in syncpt_release as kref_put_mutex() now handles the atomic nature of the operation, ensuring that no thread can acquire the syncpt_mutex after the reference count drops to zero but before syncpt_release completes its cleanup process. This approach aligns with best practices for kernel development and follows the principle of least privilege by ensuring proper synchronization without exposing unnecessary lock contention points. The mitigation effectively prevents scenarios where synchronization points could be allocated while still being cleaned up from a previous release, thereby maintaining the integrity of the graphics processing subsystem and preventing potential exploitation of concurrent access patterns that could compromise system security or stability.