CVE-2026-31721

NameCVE-2026-31721
DescriptionIn 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-4561-1, DSA-6243-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bullseye5.10.223-1vulnerable
bullseye (security)5.10.251-5vulnerable
bookworm6.1.170-3fixed
bookworm (security)6.1.172-1fixed
trixie6.12.86-1fixed
trixie (security)6.12.88-1fixed
forky, sid7.0.7-1fixed
linux-6.1 (PTS)bullseye (security)6.1.172-1~deb11u1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebookworm6.1.170-1DSA-6243-1
linuxsourcetrixie6.12.85-1
linuxsource(unstable)6.19.12-1
linux-6.1sourcebullseye6.1.170-1~deb11u1DLA-4561-1

Notes

https://git.kernel.org/linus/4e0a88254ad59f6c53a34bf5fa241884ec09e8b2 (7.0-rc7)

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