CVE-2026-31721
usb: gadget: f_hid: move list and spinlock inits from bind to alloc
- Published
- May 1, 2026
- Updated
- May 11, 2026
- Assigning CNA
- Linux
- Evidence observed
- Aug 27, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HLow · next 30 days
- Percentile
- 2.7%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_hid: move list and spinlock inits from bind to alloc There was an issue when you did the following: - setup and bind an hid gadget - open /dev/hidg0 - use the resulting fd in EPOLL_CTL_ADD - unbind the UDC - bind the UDC - use the fd in EPOLL_CTL_DEL When CONFIG_DEBUG_LIST was enabled, a list_del corruption was reported within remove_wait_queue (via ep_remove_wait_queue). After some debugging I found out that the queues, which f_hid registers via poll_wait were the problem. These were initialized using init_waitqueue_head inside hidg_bind. So effectively, the bind function re-initialized the queues while there were still items in them. The solution is to move the initialization from hidg_bind to hidg_alloc to extend their lifetimes to the lifetime of the function instance. Additionally, I found many other possibly problematic init calls in the bind function, which I moved as well.
Sources
1- f_hid-4.14-backportsPatch
Backports of three published f_hid fixes (incl. CVE-2026-31721, CVE-2026-31606) to an EOL Linux 4.14.190 Android vendor kernel, with on-device verification records.
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