CVE-2026-92519 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
riscv, bpf: Fix memory leak in bpf_jit_free
When bpf_int_jit_compile() is called for subprograms, it returns early during the first pass (!prog->is_func || extra_pass is false), keeping ctx->offset alive for the subsequent extra pass.
If JIT compilation fails for a later subprogram, the BPF core aborts and calls bpf_jit_free() to clean up the first subprogram. However, bpf_jit_free() fails to free jit_data->ctx.offset, which causes a memory leak of the JIT context offsets array.
Fix this by adding the missing kfree(jit_data->ctx.offset) in bpf_jit_free().
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Analysis
by VulDB Data Team • 09/18/2026
The Linux kernel's Berkeley Packet Filter (BPF) subsystem provides a powerful mechanism for executing sandboxed programs within the kernel, primarily used for networking and tracing purposes. A critical memory management flaw was identified in the Just-In-Time (JIT) compiler implementation for RISC-V architectures, specifically affecting how subprograms are handled during compilation and cleanup phases. The vulnerability arises from an inconsistency in resource allocation and deallocation logic when processing BPF programs that contain multiple subprogram calls. This issue highlights a gap in error handling paths within the JIT compilation workflow, leading to persistent memory leaks that can degrade system stability over time.
The technical root of the problem lies in the interaction between bpf_int_jit_compile() and bpf_jit_free(). When compiling BPF programs with subprograms, the compiler performs multiple passes to resolve offsets and generate machine code. During the initial pass, if a program is identified as a function or if an extra pass is not required, the compilation process may return early while retaining context data structures in memory. Specifically, the offset array within the JIT context remains allocated but marked for potential reuse in subsequent processing stages. If a later subprogram fails to compile due to invalid instructions or other constraints, the BPF core aborts the entire operation and initiates cleanup procedures by invoking bpf_jit_free() on previously compiled components. However, this cleanup function was incomplete; it failed to release the memory associated with jit_data->ctx.offset for earlier successful compilations that are now being discarded due to the overall failure.
This oversight results in a classic use-after-free scenario variant known as a memory leak within kernel space. Each time such an error condition is triggered, a portion of physical memory corresponding to the JIT context offsets array remains allocated but unreachable by subsequent operations. While individual leaks may appear negligible, they accumulate with repeated execution of malformed or complex BPF programs. In long-running systems, this can lead to gradual exhaustion of available kernel memory, potentially causing out-of-memory conditions that affect other critical subsystems. The impact is particularly relevant in environments where high volumes of dynamic packet filtering rules are loaded and unloaded frequently, such as in cloud-native networking stacks or advanced intrusion detection systems utilizing eBPF for real-time analysis.
From a classification perspective, this vulnerability aligns with CWE-401, which describes the failure to release memory after it has been finished being used. The lack of proper resource cleanup during error handling paths is a common source of instability in complex kernel subsystems like BPF. Furthermore, while not directly exploitable for remote code execution without additional conditions, such memory leaks contribute to Denial of Service (DoS) vectors by degrading system resources over time. In the context of MITRE ATT&CK techniques related to resource exhaustion or persistence through modified system states, this flaw represents a subtle avenue for destabilizing host integrity if an attacker can repeatedly trigger compilation failures in targeted BPF programs.
To mitigate this vulnerability, kernel developers have implemented a fix by adding the missing kfree() call within bpf_jit_free(). This ensures that when cleanup is initiated due to a subsequent failure, all previously allocated JIT context data structures are properly released back to the system memory pool. System administrators and users should apply the latest available Linux kernel updates for RISC-V architectures to resolve this issue. Additionally, developers writing BPF programs should ensure robust error handling in their applications to minimize unnecessary compilation attempts that might trigger these code paths prematurely. Regular auditing of kernel logs for out-of-memory warnings can also help detect any residual impact from unpatched systems where such leaks may have accumulated over extended periods.