In the Linux kernel, the following vulnerability has been resolved:

locking/ww_mutex/test: Fix potential workqueue corruption

In some cases running with the test-ww_mutex code, I was seeing
odd behavior where sometimes it seemed flush_workqueue was
returning before all the work threads were finished.

Often this would cause strange crashes as the mutexes would be
freed while they were being used.

Looking at the code, there is a lifetime problem as the
controlling thread that spawns the work allocates the
"struct stress" structures that are passed to the workqueue
threads. Then when the workqueue threads are finished,
they free the stress struct that was passed to them.

Unfortunately the workqueue work_struct node is in the stress
struct. Which means the work_struct is freed before the work
thread returns and while flush_workqueue is waiting.

It seems like a better idea to have the controlling thread
both allocate and free the stress structures, so that we can
be sure we don't corrupt the workqueue by freeing the structure
prematurely.

So this patch reworks the test to do so, and with this change
I no longer see the early flush_workqueue returns.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-52836
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2023/CVE-2023-52836.mbox
https://git.kernel.org/stable/c/d4d37c9e6a4dbcca958dabd99216550525c7e389
https://git.kernel.org/stable/c/d8267cabbe1bed15ccf8b0e684c528bf8eeef715
https://git.kernel.org/stable/c/dcd85e3c929368076a7592b27f541e0da8b427f5
https://git.kernel.org/stable/c/9ed2d68b3925145f5f51c46559484881d6082f75
https://git.kernel.org/stable/c/e89d0ed45a419c485bae999426ecf92697cbdda3
https://git.kernel.org/stable/c/c56df79d68677cf062da1b6e3b33e74299a92dfc
https://git.kernel.org/stable/c/e36407713163363e65566e7af0abe207d5f59a0c
https://git.kernel.org/stable/c/304a2c4aad0fff887ce493e4197bf9cbaf394479
https://git.kernel.org/stable/c/bccdd808902f8c677317cec47c306e42b93b849e
https://www.cve.org/CVERecord?id=CVE-2023-52836
https://bugzilla.redhat.com/show_bug.cgi?id=2282695