CVE-2024-26912 in Linux
Summary
by MITRE • 04/17/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/nouveau: fix several DMA buffer leaks
Nouveau manages GSP-RM DMA buffers with nvkm_gsp_mem objects. Several of these buffers are never dealloced. Some of them can be deallocated right after GSP-RM is initialized, but the rest need to stay until the driver unloads.
Also futher bullet-proof these objects by poisoning the buffer and clearing the nvkm_gsp_mem object when it is deallocated. Poisoning the buffer should trigger an error (or crash) from GSP-RM if it tries to access the buffer after we've deallocated it, because we were wrong about when it is safe to deallocate.
Finally, change the mem->size field to a size_t because that's the same type that dma_alloc_coherent expects.
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Analysis
by VulDB Data Team • 05/24/2024
The vulnerability described in CVE-2024-26912 represents a critical memory management issue within the Linux kernel's nouveau graphics driver component. This flaw specifically affects the display subsystem's handling of GSP-RM DMA buffers through the nvkm_gsp_mem object management system. The nouveau driver, which provides open-source graphics support for nvidia GPUs, contains a memory leak condition that can persist throughout system operation, potentially leading to resource exhaustion and system instability. The vulnerability stems from improper cleanup of DMA buffer allocations that should be released after GSP-RM initialization but remain allocated until driver unloading.
The technical implementation of this vulnerability involves the nvkm_gsp_mem object structure which manages memory buffers used by the GSP-RM (Graphics Services Processor - Resource Manager) component. Several DMA buffers allocated during driver initialization are never properly deallocated, creating a memory leak that accumulates over time. The issue manifests because the driver fails to implement proper cleanup routines for certain buffer objects that are no longer needed after the GSP-RM initialization phase. This memory management failure violates fundamental principles of resource lifecycle management and can lead to progressive memory consumption that eventually impacts system performance or stability.
The operational impact of this vulnerability extends beyond simple memory consumption to potentially compromise system reliability and security. When DMA buffers remain allocated unnecessarily, they consume precious system memory resources that could otherwise be utilized for legitimate system operations. The vulnerability creates a persistent resource leak that may not immediately manifest as system crashes but can lead to gradual degradation of system performance. Additionally, the improper memory management creates potential attack vectors where adversaries could exploit the leaked memory regions to gain unauthorized access or cause denial of service conditions.
The mitigation strategy implemented in the fix addresses multiple aspects of the vulnerability through comprehensive remediation measures. The solution includes adding proper deallocation routines for buffers that can be freed immediately after GSP-RM initialization, while ensuring remaining buffers are properly cleaned up during driver unloading. The implementation incorporates memory poisoning techniques where deallocated buffer contents are overwritten with invalid data patterns to detect potential attempts by GSP-RM to access freed memory. This defensive programming approach aligns with common security practices outlined in the ATT&CK framework for memory corruption mitigation. The fix also addresses a type consistency issue by changing the mem->size field from an incompatible type to size_t, which matches the expected parameter type for dma_alloc_coherent function calls and prevents potential type-related memory management errors.
This vulnerability demonstrates the importance of proper resource management in kernel-level drivers and aligns with CWE-404, which addresses improper resource release or memory leak conditions in software systems. The fix represents a comprehensive approach to memory management that includes both preventive measures against future occurrences and reactive detection mechanisms to identify misuse of freed resources. The remediation efforts also address type safety concerns that could compound the memory management issues, ensuring that the driver's memory allocation and deallocation routines maintain consistency with kernel APIs and expected parameter types. The implementation follows established best practices for kernel module development and memory management, reducing the attack surface and improving overall system stability and security posture.