CVE-2023-53779 in Linux
Summary
by MITRE • 12/09/2025
In the Linux kernel, the following vulnerability has been resolved:
mfd: dln2: Fix memory leak in dln2_probe()
When dln2_setup_rx_urbs() in dln2_probe() fails, error out_free forgets to call usb_put_dev() to decrease the refcount of dln2->usb_dev.
Fix this by adding usb_put_dev() in the error handling code of dln2_probe().
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Analysis
by VulDB Data Team • 03/29/2026
This vulnerability resides within the Linux kernel's multi-function device driver framework, specifically affecting the dln2 driver which handles USB communication devices. The issue manifests as a memory leak during device probe operations when the driver fails to properly manage reference counting for USB device structures. The flaw occurs in the dln2_probe() function where dln2_setup_rx_urbs() encounters an error condition, leading to incomplete resource cleanup and subsequent memory leaks.
The technical implementation of this vulnerability stems from improper reference counting mechanics within the USB subsystem integration. When dln2_setup_rx_urbs() fails during the device initialization process, the error handling path executes a code branch that neglects to decrement the reference count of the USB device structure through usb_put_dev(). This function call is essential for proper resource management and ensures that the USB device object can be safely freed when no longer needed. The omission creates a dangling reference that prevents the kernel from reclaiming memory associated with the USB device, leading to gradual memory consumption over time.
The operational impact of this vulnerability extends beyond simple memory waste, potentially affecting system stability and performance in embedded or resource-constrained environments where memory management is critical. Attackers could exploit this weakness by repeatedly probing and failing to initialize the dln2 device, causing progressive memory exhaustion that might lead to system instability or denial of service conditions. The leak occurs during normal device operation when hardware initialization fails, making it particularly concerning for systems that frequently interact with USB devices or experience intermittent connection issues.
This vulnerability aligns with CWE-401, which specifically addresses improper resource release or memory leaks in software systems. The flaw represents a classic case of resource management failure where proper cleanup routines are bypassed during error conditions, violating fundamental principles of safe programming practices in kernel space. From an attack perspective, this issue could be classified under the ATT&CK technique T1499.004 for "Resource Hijacking" as it consumes system resources without proper release, potentially enabling persistent resource exhaustion attacks against affected systems.
The recommended mitigation involves implementing the straightforward fix of adding usb_put_dev() to the error handling code path within dln2_probe(). This ensures that regardless of whether dln2_setup_rx_urbs() succeeds or fails, the USB device reference count is properly decremented. The fix requires modification to the existing error handling logic to include proper cleanup calls before returning from the probe function. System administrators should apply kernel updates containing this fix as soon as possible, particularly in production environments where resource consumption monitoring is critical. Additionally, comprehensive testing should validate that the fix does not introduce regression issues in normal device operation scenarios where initialization succeeds as expected.