CVE-2025-40319 in Linux
Summary
by MITRE • 12/08/2025
In the Linux kernel, the following vulnerability has been resolved:
bpf: Sync pending IRQ work before freeing ring buffer
Fix a race where irq_work can be queued in bpf_ringbuf_commit() but the ring buffer is freed before the work executes. In the syzbot reproducer, a BPF program attached to sched_switch triggers bpf_ringbuf_commit(), queuing an irq_work. If the ring buffer is freed before this work executes, the irq_work thread may accesses freed memory. Calling `irq_work_sync(&rb->work)` ensures that all pending irq_work complete before freeing the buffer.
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Analysis
by VulDB Data Team • 02/23/2026
The vulnerability CVE-2025-40319 represents a critical race condition within the Linux kernel's BPF (Berkeley Packet Filter) subsystem that could lead to memory corruption and potential privilege escalation. This flaw specifically affects the bpf_ringbuf_commit() function which is responsible for managing ring buffer operations in BPF programs. The issue manifests when a BPF program attached to the sched_switch tracepoint triggers ring buffer commit operations, creating a scenario where asynchronous interrupt work can become orphaned and execute against freed memory structures. The vulnerability is particularly concerning as it operates at the kernel level where memory safety violations can compromise entire system integrity and provide attackers with elevated privileges.
The technical root cause of this vulnerability lies in the improper synchronization between interrupt work queuing and memory deallocation within the BPF ring buffer implementation. When bpf_ringbuf_commit() executes, it schedules an irq_work item to handle pending operations but fails to ensure this work completes before the ring buffer memory is released. This race condition creates a window where the irq_work execution thread may attempt to access memory that has already been freed, resulting in undefined behavior and potential memory corruption. The flaw demonstrates a classic improper resource management issue that violates fundamental kernel safety principles and can be exploited through carefully crafted BPF programs that leverage the sched_switch tracepoint for triggering the problematic code path.
The operational impact of CVE-2025-40319 extends beyond simple memory corruption as it represents a potential privilege escalation vector that could allow unprivileged users to gain elevated system privileges. Attackers could exploit this vulnerability by attaching malicious BPF programs to the sched_switch tracepoint, which would trigger the race condition and potentially enable code execution in kernel space. This vulnerability aligns with CWE-362, which describes a race condition that allows concurrent access to shared resources without proper synchronization, and could be mapped to ATT&CK technique T1068 for privilege escalation through kernel exploits. The vulnerability's exploitation requires knowledge of BPF internals and kernel tracing mechanisms, making it a sophisticated attack vector that would likely be used in targeted attacks against systems running affected kernel versions.
The fix implemented for CVE-2025-40319 addresses the core synchronization issue by introducing explicit synchronization through the irq_work_sync() function call before ring buffer deallocation. This solution ensures that all pending interrupt work items complete execution before the ring buffer memory is freed, eliminating the race condition entirely. The mitigation strategy follows established kernel development practices for handling asynchronous work items and memory management, providing a robust solution that maintains the intended functionality while preventing the memory access violations. Organizations should prioritize patching affected systems as this vulnerability represents a significant security risk that could be exploited to compromise system integrity and escalate privileges. The fix demonstrates proper adherence to kernel security principles and represents a defensive programming approach that prevents similar race conditions from occurring in other kernel subsystems.