CVE-2023-53234 in Linux
Summary
by MITRE • 09/15/2025
In the Linux kernel, the following vulnerability has been resolved:
watchdog: Fix kmemleak in watchdog_cdev_register
kmemleak reports memory leaks in watchdog_dev_register, as follows: unreferenced object 0xffff888116233000 (size 2048): comm ""modprobe"", pid 28147, jiffies 4353426116 (age 61.741s) hex dump (first 32 bytes): 80 fa b9 05 81 88 ff ff 08 30 23 16 81 88 ff ff .........0#..... 08 30 23 16 81 88 ff ff 00 00 00 00 00 00 00 00 .0#............. backtrace: [<000000007f001ffd>] __kmem_cache_alloc_node+0x157/0x220
[<000000006a389304>] kmalloc_trace+0x21/0x110
[<000000008d640eea>] watchdog_dev_register+0x4e/0x780 [watchdog]
[<0000000053c9f248>] __watchdog_register_device+0x4f0/0x680 [watchdog]
[<00000000b2979824>] watchdog_register_device+0xd2/0x110 [watchdog]
[<000000001f730178>] 0xffffffffc10880ae
[<000000007a1a8bcc>] do_one_initcall+0xcb/0x4d0
[<00000000b98be325>] do_init_module+0x1ca/0x5f0
[<0000000046d08e7c>] load_module+0x6133/0x70f0
...
unreferenced object 0xffff888105b9fa80 (size 16): comm ""modprobe"", pid 28147, jiffies 4353426116 (age 61.741s) hex dump (first 16 bytes): 77 61 74 63 68 64 6f 67 31 00 b9 05 81 88 ff ff watchdog1....... backtrace: [<000000007f001ffd>] __kmem_cache_alloc_node+0x157/0x220
[<00000000486ab89b>] __kmalloc_node_track_caller+0x44/0x1b0
[<000000005a39aab0>] kvasprintf+0xb5/0x140
[<0000000024806f85>] kvasprintf_const+0x55/0x180
[<000000009276cb7f>] kobject_set_name_vargs+0x56/0x150
[<00000000a92e820b>] dev_set_name+0xab/0xe0
[<00000000cec812c6>] watchdog_dev_register+0x285/0x780 [watchdog]
[<0000000053c9f248>] __watchdog_register_device+0x4f0/0x680 [watchdog]
[<00000000b2979824>] watchdog_register_device+0xd2/0x110 [watchdog]
[<000000001f730178>] 0xffffffffc10880ae
[<000000007a1a8bcc>] do_one_initcall+0xcb/0x4d0
[<00000000b98be325>] do_init_module+0x1ca/0x5f0
[<0000000046d08e7c>] load_module+0x6133/0x70f0
...
The reason is that put_device is not be called if cdev_device_add fails and wdd->id != 0.
watchdog_cdev_register wd_data = kzalloc [1]
err = dev_set_name [2]
.. err = cdev_device_add if (err) {
if (wdd->id == 0) { // wdd->id != 0
.. } return err; // [1],[2] would be leaked
To fix it, call put_device in all wdd->id cases.
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Analysis
by VulDB Data Team • 03/16/2026
The vulnerability identified as CVE-2023-53234 resides within the Linux kernel's watchdog subsystem, specifically in the watchdog_cdev_register function where memory leaks occur due to improper resource management. This issue manifests through kmemleak reports indicating unreferenced memory objects that remain allocated even after the watchdog device registration process has completed. The flaw affects the kernel's ability to properly clean up allocated resources during error conditions, leading to potential memory exhaustion over time. The vulnerability is classified under CWE-401 as a failure to release memory resources, which represents a direct memory leak condition that can degrade system performance and stability.
The technical root cause stems from the watchdog device registration process where the function fails to properly invoke put_device when cdev_device_add encounters an error condition and the watchdog device identifier (wdd->id) is non-zero. During normal operation, the watchdog subsystem allocates memory for device data structures using kzalloc and sets device names using dev_set_name, but when cdev_device_add fails, the code path does not properly release previously allocated resources. The conditional logic in the error handling section only calls put_device when wdd->id equals zero, leaving memory allocated when wdd->id is non-zero. This creates a resource leak scenario where kernel memory becomes permanently unavailable for reuse, as evidenced by the backtrace showing allocation paths through __kmem_cache_alloc_node and kmalloc_trace.
The operational impact of this vulnerability extends beyond simple memory consumption, as it can lead to progressive system degradation and potential denial of service conditions. When the watchdog subsystem is repeatedly invoked or when multiple watchdog devices are registered, the accumulated memory leaks can consume significant portions of available kernel memory. The vulnerability is particularly concerning in embedded systems or server environments where watchdog functionality is critical for system monitoring and recovery. Attackers could potentially exploit this memory leak to cause system instability or force system reboots through resource exhaustion, making this a significant concern for system administrators and security professionals managing Linux-based infrastructure.
Mitigation strategies for CVE-2023-53234 involve implementing proper resource cleanup in all code paths within the watchdog subsystem. The fix requires modifying the watchdog_cdev_register function to ensure that put_device is called regardless of the wdd->id value or error conditions encountered during device registration. This approach aligns with the ATT&CK framework's defense evasion techniques by ensuring proper resource management and preventing memory leaks that could be exploited for persistent system disruption. System administrators should update to kernel versions containing the patched watchdog subsystem code, and monitoring tools should be configured to detect memory allocation patterns that might indicate similar resource management issues. The fix demonstrates proper defensive programming practices that should be applied across kernel subsystems to prevent similar memory leak vulnerabilities from occurring in other components of the operating system.