CVE-2024-53213 in Linux
Summary
by MITRE • 12/27/2024
In the Linux kernel, the following vulnerability has been resolved:
net: usb: lan78xx: Fix double free issue with interrupt buffer allocation
In lan78xx_probe(), the buffer `buf` was being freed twice: once implicitly through `usb_free_urb(dev->urb_intr)` with the `URB_FREE_BUFFER` flag and again explicitly by `kfree(buf)`. This caused a double free issue.
To resolve this, reordered `kmalloc()` and `usb_alloc_urb()` calls to simplify the initialization sequence and removed the redundant `kfree(buf)`. Now, `buf` is allocated after `usb_alloc_urb()`, ensuring it is correctly managed by `usb_fill_int_urb()` and freed by `usb_free_urb()` as intended.
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Analysis
by VulDB Data Team • 06/01/2026
The vulnerability described in CVE-2024-53213 represents a critical double free condition within the Linux kernel's usb ethernet driver implementation, specifically affecting the lan78xx device family. This flaw exists in the network subsystem's handling of interrupt buffer allocation for USB-based ethernet adapters, creating a potential pathway for memory corruption and system instability. The issue stems from improper memory management practices during device probe initialization, where the kernel's USB driver framework encounters a scenario where the same memory buffer undergoes two consecutive deallocation operations. The lan78xx driver, which supports various USB ethernet devices including the LAN7800 and LAN7850 chipsets, demonstrates a fundamental error in resource management that directly violates established memory safety principles. When a device is probed and initialized, the driver attempts to allocate memory for interrupt handling while simultaneously managing USB transfer requests through the kernel's USB subsystem.
The technical root cause of this vulnerability lies in the improper sequencing of memory allocation and USB resource management calls within the lan78xx_probe() function. Specifically, the driver first allocates a buffer using kmalloc() and then passes this buffer to usb_alloc_urb() which is configured with the URB_FREE_BUFFER flag. This flag instructs the USB subsystem to automatically free the buffer when usb_free_urb() is called, making the subsequent explicit kfree(buf) call redundant and dangerous. The double free condition occurs because the kernel's memory allocator receives two separate requests to free the same memory address, leading to potential memory corruption, heap tampering, and undefined behavior. This type of vulnerability falls under CWE-415 which specifically addresses double free conditions in memory management, where a program attempts to free the same memory block twice. The flaw demonstrates poor understanding of the USB subsystem's memory management semantics and violates fundamental principles of resource lifecycle management in kernel space.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling privilege escalation and system compromise. When an attacker can trigger the device probe sequence on a vulnerable system, they may be able to manipulate the memory layout and cause the kernel to execute arbitrary code or crash the system entirely. This vulnerability affects systems running Linux kernels with the affected USB ethernet driver, particularly those supporting USB-to-ethernet adapters. The attack surface is broad as any system with USB ethernet devices connected or those that might automatically probe such devices could be vulnerable. The vulnerability is particularly concerning because it exists in kernel space where memory corruption can lead to complete system compromise, making it a high-severity issue according to standard security frameworks. The potential for exploitation increases when the vulnerable device is connected to a system and the driver is loaded, as the double free condition can be triggered through normal device enumeration and initialization processes.
Mitigation strategies for this vulnerability require immediate kernel updates and patches from the Linux kernel maintainers, as the fix involves correcting the driver's resource management sequence. The recommended approach involves reordering the allocation calls to ensure proper resource handling, specifically by allocating the buffer after usb_alloc_urb() rather than before it. This ensures that the buffer is managed entirely by the USB subsystem through the URB_FREE_BUFFER flag, eliminating the redundant kfree() call that caused the double free condition. System administrators should prioritize applying the latest kernel patches that contain this fix, which are typically available through standard distribution update mechanisms. Additionally, monitoring for unusual system behavior or kernel oops messages may help detect exploitation attempts, though the vulnerability is primarily exploitable through controlled device attachment scenarios. The fix addresses the core memory management issue and aligns with established security best practices for kernel driver development, ensuring proper resource lifecycle management and preventing similar vulnerabilities in the future. This vulnerability highlights the importance of careful resource management in kernel space and demonstrates how seemingly simple programming errors can lead to critical security flaws that may affect system integrity and availability.