CVE-2022-50304 in Linux
Summary
by MITRE • 09/15/2025
In the Linux kernel, the following vulnerability has been resolved:
mtd: core: fix possible resource leak in init_mtd()
I got the error report while inject fault in init_mtd():
sysfs: cannot create duplicate filename '/devices/virtual/bdi/mtd-0' Call Trace: <TASK> dump_stack_lvl+0x67/0x83 sysfs_warn_dup+0x60/0x70 sysfs_create_dir_ns+0x109/0x120 kobject_add_internal+0xce/0x2f0 kobject_add+0x98/0x110 device_add+0x179/0xc00 device_create_groups_vargs+0xf4/0x100 device_create+0x7b/0xb0 bdi_register_va.part.13+0x58/0x2d0 bdi_register+0x9b/0xb0 init_mtd+0x62/0x171 [mtd]
do_one_initcall+0x6c/0x3c0 do_init_module+0x58/0x222 load_module+0x268e/0x27d0 __do_sys_finit_module+0xd5/0x140 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK> kobject_add_internal failed for mtd-0 with -EEXIST, don't try to register things with the same name in the same directory. Error registering mtd class or bdi: -17
If init_mtdchar() fails in init_mtd(), mtd_bdi will not be unregistered, as a result, we can't load the mtd module again, to fix this by calling bdi_unregister(mtd_bdi) after out_procfs label.
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Analysis
by VulDB Data Team • 01/10/2026
The vulnerability CVE-2022-50304 represents a resource leak in the Linux kernel's MTD (Memory Technology Device) subsystem, specifically within the init_mtd() function. This issue arises from improper resource management during module initialization, creating a persistent state where the MTD subsystem cannot be reloaded due to naming conflicts in the sysfs filesystem. The flaw manifests when the kernel attempts to register MTD devices and encounters a duplicate filename error in the virtual device hierarchy, specifically the path '/devices/virtual/bdi/mtd-0'. This error condition triggers a cascade of failures that prevent proper module unloading and subsequent reloading operations, effectively creating a denial of service scenario for MTD functionality.
The technical root cause stems from a missing cleanup operation in the error handling path of the init_mtd() function. When init_mtdchar() fails during initialization, the code path does not properly unregister the previously allocated mtd_bdi (block device information) structure, leading to a resource leak. This violates the fundamental principle of resource management where all allocated resources must be properly released regardless of execution path taken. The error code -17 (EEXIST) indicates that the system is attempting to create a sysfs entry that already exists, which occurs because the bdi_unregister() call is omitted when the function exits via the out_procfs label. This failure to clean up creates a persistent state where subsequent module loading attempts fail with duplicate entry errors, as the kernel maintains references to already-registered resources.
The operational impact of this vulnerability extends beyond simple module reloading failures, affecting system stability and maintenance operations in embedded systems and devices that heavily rely on MTD functionality. In production environments, this could lead to complete module unavailability requiring system reboot for recovery, particularly impacting IoT devices, embedded systems, and storage appliances that utilize MTD drivers for flash memory management. The vulnerability is particularly concerning in environments where dynamic module loading and unloading are common, as it creates a persistent failure state that can cascade into broader system instability. This aligns with CWE-404, which addresses improper resource release or cleanup, and represents a classic case of resource leak in kernel space operations. The ATT&CK framework would categorize this under privilege escalation through resource exhaustion or denial of service, as an attacker could potentially exploit this to prevent legitimate MTD operations.
Mitigation strategies should focus on ensuring proper resource cleanup in all error handling paths of kernel modules. The fix implemented in the patch requires calling bdi_unregister(mtd_bdi) after the out_procfs label to ensure that the block device information structure is properly released even when initialization fails. System administrators should prioritize applying kernel updates that contain this fix, particularly in embedded environments where module reloading is frequent. Additionally, monitoring systems should be implemented to detect and alert on module loading failures that may indicate this resource leak condition. The vulnerability demonstrates the critical importance of defensive programming practices in kernel space, where every resource allocation must have a corresponding deallocation regardless of execution flow, and proper error handling must account for all possible failure scenarios to prevent resource exhaustion and system instability.