CVE-2026-64033 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
RDMA/rtrs: Fix use-after-free in path file creation cleanup
In the error path of rtrs_srv_create_path_files(), the sysfs root folders may already have been created and srv_path->kobj may already have been initialized. If a later step fails, the cleanup currently calls kobject_put(&srv_path->kobj) before rtrs_srv_destroy_once_sysfs_root_folders(srv_path).
kobject_put() may drop the last reference to srv_path->kobj and invoke the release callback, rtrs_srv_release(), which frees srv_path. The following call to rtrs_srv_destroy_once_sysfs_root_folders(srv_path) then dereferences srv_path internally to access srv_path->srv, resulting in a use-after-free.
This failure path is reached before rtrs_srv_create_path_files() returns success, so the successful-path lifetime handling is not involved.
Fix this by destroying the sysfs root folders before calling kobject_put(&srv_path->kobj), so srv_path is still valid while the helper accesses it.
This issue was found by a static analysis tool I am developing.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/20/2026
The vulnerability resides within the Linux kernel's RDMA/rtrs subsystem where a use-after-free condition occurs during path file creation cleanup operations. This flaw manifests in the rtrs_srv_create_path_files() function's error handling path, specifically when sysfs root folders have already been established and the srv_path->kobj has been initialized but subsequent operations fail. The problematic sequence involves calling kobject_put(&srv_path->kobj) before invoking rtrs_srv_destroy_once_sysfs_root_folders(srv_path), creating a temporal gap where memory management conflicts can occur.
The technical flaw stems from improper cleanup ordering in the kernel's object reference management system. When kobject_put() executes, it may reduce the reference count to zero and trigger the release callback rtrs_srv_release(), which consequently frees the srv_path structure. However, the subsequent call to rtrs_srv_destroy_once_sysfs_root_folders(srv_path) attempts to access srv_path->srv members, resulting in a use-after-free scenario that directly violates memory safety principles. This condition represents a classic race condition where object lifetime management conflicts with cleanup operations.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling privilege escalation attacks or system instability. Attackers could exploit this flaw to manipulate kernel memory structures and potentially gain elevated privileges within the system. The vulnerability affects systems utilizing RDMA (Remote Direct Memory Access) functionality through the rtrs protocol, particularly those implementing storage server services that rely on sysfs object creation and management. According to CWE classification, this represents a CWE-416: Use After Free vulnerability, while ATT&CK framework would categorize this under privilege escalation techniques leveraging kernel memory corruption.
The fix implements proper cleanup ordering by ensuring sysfs root folders are destroyed before calling kobject_put(&srv_path->kobj), thereby preserving srv_path validity during the helper function's execution. This remediation aligns with kernel security best practices for object lifetime management and follows established patterns for preventing use-after-free conditions in kernel space. The vulnerability was identified through static analysis, demonstrating the effectiveness of automated security tools in detecting complex kernel memory management issues that may elude traditional testing approaches. This fix ensures proper sequential cleanup operations while maintaining the integrity of kernel object references throughout the error handling path.