CVE-2021-47026

In the Linux kernel, the following vulnerability has been resolved:
RDMA/rtrs-clt: destroy sysfs after removing session from active list A
session can be removed dynamically by sysfs interface “remove_path” that
eventually calls rtrs_clt_remove_path_from_sysfs function. The current
rtrs_clt_remove_path_from_sysfs first removes the sysfs interfaces and
frees sess->stats object. Second it removes the session from the active
list. Therefore some functions could access non-connected session and
access the freed sess->stats object even-if they check the session status
before accessing the session. For instance rtrs_clt_request and
get_next_path_min_inflight check the session status and try to send IO to
the session. The session status could be changed when they are trying to
send IO but they could not catch the change and update the statistics
information in sess->stats object, and generate use-after-free problem.
(see: “RDMA/rtrs-clt: Check state of the rtrs_clt_sess before reading its
stats”) This patch changes the rtrs_clt_remove_path_from_sysfs to remove
the session from the active session list and then destroy the sysfs
interfaces. Each function still should check the session status because
closing or error recovery paths can change the status.