A use-after-free vulnerability was found in the Linux kernel through io_uring and the IORING_OP_SPLICE operation. IORING_OP_SPLICE is missing the IO_WQ_WORK_FILES flag, which signals that the operation won't use current->nsproxy, so its reference counter is not increased. This assumption is not always true as calling io_splice on specific files will call the get_uts function which will use current->nsproxy leading to invalidly decreasing its reference counter later causing the use-after-free vulnerability. Upstream commit: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=75454b4bbfc7e6a4dd8338556f36ea9107ddf61a
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 2164425]
This was fixed for Fedora with the 5.12 rebases.
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2022-4696