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

bfq: Make sure bfqg for which we are queueing requests is online

Bios queued into BFQ IO scheduler can be associated with a cgroup that
was already offlined. This may then cause insertion of this bfq_group
into a service tree. But this bfq_group will get freed as soon as last
bio associated with it is completed leading to use after free issues for
service tree users. Fix the problem by making sure we always operate on
online bfq_group. If the bfq_group associated with the bio is not
online, we pick the first online parent.

https://git.kernel.org/stable/c/075a53b78b815301f8d3dd1ee2cd99554e34f0dd

https://git.kernel.org/stable/c/51f724bffa3403a5236597e6b75df7329c1ec6e9

https://git.kernel.org/stable/c/6ee0868b0c3ccead5907685fcdcdd0c08dfe4b0b

https://git.kernel.org/stable/c/7781c38552e6cc54ed8e9040279561340516b881

https://git.kernel.org/stable/c/97bd6c56bdcb41079e488e31df56809e3b2ce628

https://git.kernel.org/stable/c/ccddf8cd411c1800863ed357064e56ceffd356bb