CVE-2026-31721

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> usb: gadget: f_hid: move list and spinlock inits from bind to alloc<br /> <br /> There was an issue when you did the following:<br /> - setup and bind an hid gadget<br /> - open /dev/hidg0<br /> - use the resulting fd in EPOLL_CTL_ADD<br /> - unbind the UDC<br /> - bind the UDC<br /> - use the fd in EPOLL_CTL_DEL<br /> <br /> When CONFIG_DEBUG_LIST was enabled, a list_del corruption was reported<br /> within remove_wait_queue (via ep_remove_wait_queue). After some<br /> debugging I found out that the queues, which f_hid registers via<br /> poll_wait were the problem. These were initialized using<br /> init_waitqueue_head inside hidg_bind. So effectively, the bind function<br /> re-initialized the queues while there were still items in them.<br /> <br /> The solution is to move the initialization from hidg_bind to hidg_alloc<br /> to extend their lifetimes to the lifetime of the function instance.<br /> <br /> Additionally, I found many other possibly problematic init calls in the<br /> bind function, which I moved as well.