In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Check resize_disabled before publishing the new subbuf order ring_buffer_subbuf_order_set() stores the new order and only then walks the CPUs, returning -EBUSY if any of them has resizing disabled. A user mapped buffer has resizing disabled, and __rb_map_vma() reads buffer->subbuf_order without buffer->mutex, so an mmap of an already mapped CPU racing the failing order change sizes the mapping with the new order and inserts pages past the sub-buffer into the VMA. Check the CPUs before storing the new order.
https://git.kernel.org/stable/c/f2099644e1b2a2c0805c5240d63ab0522d9d0174
https://git.kernel.org/stable/c/d860c67c051685abb0460b593b193f0f45f4fa92
https://git.kernel.org/stable/c/9fd4ea952e6ac12a63c3fe89f08ad02771aa2c06
https://git.kernel.org/stable/c/32bf47db9237c5b8b6f6aaa5356bb4c79d241f76