CVE-2026-31721
MEDIUM SEVERITYCVSS Score & Metrics
Base Score
5.5 / 10
Vector String
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Vulnerability Description
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.
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.
Vulnerability Details
Published Date
Last Modified
CWE ID
NVD-CWE-noinfo
Source
NVD
Vendor
Linux
Product
Linux
External References
- https://git.kernel.org/stable/c/13440c0db227c5db01da751ed966dde4cdd2ea18
- https://git.kernel.org/stable/c/26a879a41ed960b3fb4ec773ef2788c515c0e488
- https://git.kernel.org/stable/c/4e0a88254ad59f6c53a34bf5fa241884ec09e8b2
- https://git.kernel.org/stable/c/5d1bb391ceeebb28327703dd07af8c6324af298f
- https://git.kernel.org/stable/c/81aee4500055876883658b024b6fb61801afe134
- https://git.kernel.org/stable/c/8ec6a58586f195a88479edcdb0b8027c39f12d03
- https://git.kernel.org/stable/c/de93e0862169b5539e00c2b9980b93fd80c37c0d
- https://git.kernel.org/stable/c/f7d00ee1c8082c8a134340aaf16d71a27e29c362
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