usb: class: cdc-wdm: fix reordering issue in read code path
In the Linux kernel, the following vulnerability has been resolved: usb: class: cdc-wdm: fix reordering issue in read code path Quoting the bug report: Due to compiler optimization or CPU out-of-order execution, the desc->length update can be reordered before the memmove. If this happens, wdm_read() can see the new length and call copy_to_user() on uninitialized memory. This also violates LKMM data race rules [1]. Fix it by using WRITE_ONCE and memory barriers.
02 / AFFECTED SOFTWARE
Affected packages
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: usb: class: cdc-wdm: fix reordering issue in read code path Quoting the bug report: Due to compiler optimization or CPU out-of-order execution, the desc->length update can be reordered before the memmove. If this happens, wdm_read() can see the new length and call copy_to_user() on uninitialized memory. This also violates LKMM data race rules [1]. Fix it by using WRITE_ONCE and memory barriers.
05 / REFERENCES
Further evidence
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- https://git.kernel.org/stable/c/170e8daca24da6edb4be82ab01abf44e87af387b
- https://git.kernel.org/stable/c/276aef0fd2b92f41b920ac891c72cadeee957934
- https://git.kernel.org/stable/c/4ee3062bf2c9a722afef429826e8607eaf3fc6a0
- https://git.kernel.org/stable/c/638328ca9c17ae6511ad62198c57bae32ffa3c91
- https://git.kernel.org/stable/c/67ed312124bb1b61858778ac0b985b48961c862a
- https://git.kernel.org/stable/c/8df672bfe3ec2268c2636584202755898e547173
- https://git.kernel.org/stable/c/c8fa96ed021923dae147bcd9f9205b8df7b82360
- https://git.kernel.org/stable/c/e3c874b05901dc519054b5107d16620e6d2b5fea
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43427.json
- https://nvd.nist.gov/vuln/detail/CVE-2026-43427