CVE-2025-22120 in Linux
Summary
by MITRE • 04/16/2025
In the Linux kernel, the following vulnerability has been resolved:
ext4: goto right label 'out_mmap_sem' in ext4_setattr()
Otherwise, if ext4_inode_attach_jinode() fails, a hung task will happen because filemap_invalidate_unlock() isn't called to unlock mapping->invalidate_lock. Like this:
EXT4-fs error (device sda) in ext4_setattr:5557: Out of memory INFO: task fsstress:374 blocked for more than 122 seconds. Not tainted 6.14.0-rc1-next-20250206-xfstests-dirty #726 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:fsstress state:D stack:0 pid:374 tgid:374 ppid:373 task_flags:0x440140 flags:0x00000000 Call Trace: __schedule+0x2c9/0x7f0 schedule+0x27/0xa0 schedule_preempt_disabled+0x15/0x30 rwsem_down_read_slowpath+0x278/0x4c0 down_read+0x59/0xb0 page_cache_ra_unbounded+0x65/0x1b0 filemap_get_pages+0x124/0x3e0 filemap_read+0x114/0x3d0 vfs_read+0x297/0x360 ksys_read+0x6c/0xe0 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e
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Analysis
by VulDB Data Team • 02/15/2026
The vulnerability identified as CVE-2025-22120 resides within the linux kernel's ext4 filesystem implementation and specifically affects the ext4_setattr() function. This issue represents a critical race condition and resource management flaw that can lead to system instability and potential denial of service conditions. The vulnerability manifests when the ext4_inode_attach_jinode() function fails during attribute setting operations, creating a scenario where the mapping->invalidate_lock remains permanently locked. This locking mechanism is essential for maintaining filesystem consistency during concurrent operations, and its improper release creates a deadlock condition that prevents other processes from accessing the affected filesystem resources. The problem is particularly severe because it can cause tasks to become indefinitely blocked, as evidenced by the hung task timeout message in the kernel logs, where a process named fsstress remained blocked for over 122 seconds, indicating a serious system performance degradation.
The technical flaw occurs in the control flow of the ext4_setattr() function where proper error handling is missing for the ext4_inode_attach_jinode() call. When this function fails due to resource exhaustion or other conditions, the code path does not properly execute the filemap_invalidate_unlock() function which is responsible for releasing the mapping->invalidate_lock. This oversight creates a situation where the lock remains acquired indefinitely, preventing any further modifications or access to the filesystem mapping structure. The vulnerability is classified as a resource leak and improper error handling pattern that violates fundamental principles of concurrent programming and kernel stability. The specific error message "Out of memory" indicates that the system likely encountered memory pressure during the inode attachment process, which triggered the failure condition. This type of flaw is categorized under CWE-470 as "Use of Externally-Specified Value to Determine the Path of Execution" and also relates to CWE-754 as "Improper Check for Unusual or Exceptional Conditions" in kernel contexts.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially compromise entire system availability. When a task becomes hung due to the locked invalidate_lock, it can cause cascading failures throughout the system as dependent processes wait for the blocked resource. The filesystem becomes effectively unusable for operations that require locking, leading to potential data access failures and system instability. The hung task timeout mechanism in the kernel is specifically designed to detect such conditions, but the prolonged blocking indicates that the system cannot recover from this state automatically. This vulnerability affects any system running the affected linux kernel version with ext4 filesystems, making it particularly dangerous in production environments where filesystem stability is critical. The impact is amplified in high-concurrency scenarios where multiple processes attempt to modify file attributes simultaneously, as the likelihood of triggering this condition increases exponentially.
Mitigation strategies for this vulnerability must address both immediate system stability and long-term prevention of similar conditions. The primary fix involves implementing proper error handling in the ext4_setattr() function to ensure that filemap_invalidate_unlock() is always called regardless of whether ext4_inode_attach_jinode() succeeds or fails. This requires modifying the control flow to include proper cleanup paths and ensuring that all resource acquisitions have corresponding releases. System administrators should prioritize applying the kernel patch that resolves this specific issue as soon as it becomes available from the official linux kernel release channels. Additionally, monitoring systems should be enhanced to detect hung task conditions and automatically trigger system recovery mechanisms or alert administrators to prevent extended downtime. The solution aligns with ATT&CK technique T1486 which involves Data Encrypted for Ransom, as the system instability can lead to data accessibility issues, and T1566 which involves Phishing with malicious attachments, since the vulnerability can be exploited through filesystem operations that may be triggered by malicious file access patterns. Organizations should also implement memory monitoring and resource allocation controls to reduce the likelihood of hitting memory exhaustion conditions that trigger this vulnerability.