CVE-2026-68373wifi: at76c50x-usb: avoid length underflow in at76_guess_freq()

Official description

In the Linux kernel, the following vulnerability has been resolved: wifi: at76c50x-usb: avoid length underflow in at76_guess_freq() at76_guess_freq() checks only that the received frame is at least a bare 802.11 header (24 bytes) before subtracting the fixed management-body offset: len -= el_off; For both beacon and probe response frames, el_off is 36. If the frame is shorter than el_off, subtracting it causes the calculated IE length to wrap. The length is eventually passed to cfg80211_find_elem_match() as a very large unsigned value, so the element walk runs beyond the RX skb. This path is reached from at76_rx_tasklet() while scanning. If the device delivers a truncated beacon or probe response, the oversized IE length causes an out-of-bounds read during scanning. Skip the IE lookup if the frame does not reach the variable elements, before subtracting el_off.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/cb831aff2f850f72bc5ff5ad77d0a70bb5a84061
• https://git.kernel.org/stable/c/4875680d1703f56afa6257ba30244f2fb44ed205
• https://git.kernel.org/stable/c/b406f33d234f98c8b310fdab5cbb492d85e98e49
• https://git.kernel.org/stable/c/e165a1d295e7e814e13b0f92c86e5d48309509ce
• https://git.kernel.org/stable/c/bcde7249d45f52f994a9872bedf45994472ade77
• https://git.kernel.org/stable/c/fb1b50ab699211e777dca5ccfb648788b6a6e519
• https://git.kernel.org/stable/c/f742d9c98b5c504fc9e6744eef13a721c2aea486
• https://git.kernel.org/stable/c/61a799ffd1e5a4fd3702d547828b7ff3d161468e