CVE-2021-47026: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47026 affects the Linux kernel's RDMA/rtrs-clt (Remote Direct Memory Access/RTRS Client) component. The vulnerability was discovered in the rtrs_clt_remove_path_from_sysfs function, where a race condition could lead to a use-after-free issue. The vulnerability affects Linux kernel versions from 5.8 through 5.10.36, 5.11 through 5.11.20, and 5.12 through 5.12.3 (NVD).

The vulnerability exists in the rtrs_clt_remove_path_from_sysfs function's implementation. The function first removes sysfs interfaces and frees sess->stats object before removing the session from the active list. This ordering allows other functions like rtrs_clt_request and get_next_path_min_inflight to potentially access a non-connected session and its freed sess->stats object, even when checking the session status. The CVSS v3.1 base score is 7.8 HIGH with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability can lead to use-after-free issues when accessing the freed sess->stats object, potentially resulting in system crashes, memory corruption, or privilege escalation (NVD).

The vulnerability requires local access and low privileges to exploit. It can be triggered through the sysfs interface 'remove_path' that calls the vulnerable rtrs_clt_remove_path_from_sysfs function (Kernel Patch).

The issue has been fixed by changing the order of operations in rtrs_clt_remove_path_from_sysfs to remove the session from the active session list before destroying the sysfs interfaces. The fix was implemented in the Linux kernel through patch 7f4a8592ff29f19c5a2ca549d0973821319afaad (Kernel Patch).