CVE-2026-72157net: thunderbolt: Fix frags[] overflow by bounding frame_count

Official description

In the Linux kernel, the following vulnerability has been resolved: net: thunderbolt: Fix frags[] overflow by bounding frame_count tbnet_poll() assembles a multi-frame ThunderboltIP packet into one skb. The first frame goes into the skb linear area and every further frame is added as a page fragment. skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, hdr_size, frame_size, TBNET_RX_PAGE_SIZE - hdr_size); A packet of frame_count frames therefore ends up with frame_count - 1 fragments. tbnet_check_frame() only bounds the peer supplied frame_count to TBNET_RING_SIZE / 4 (64), which is far above MAX_SKB_FRAGS (17 by default). A peer that sends a packet of 19 or more small frames pushes nr_frags past MAX_SKB_FRAGS, so skb_add_rx_frag() writes past skb_shinfo()->frags[] and corrupts memory after the shared info. Tighten the start of packet bound to MAX_SKB_FRAGS + 1 so a packet can never produce more fragments than frags[] can hold. This matches the recent skb frags overflow fixes in other receive paths, for example f0813bcd2d9d ("net: wwan: t7xx: fix potential skb->frags overflow in RX path") and 600dc40554dc ("net: usb: cdc-phonet: fix skb frags[] overflow in rx_complete()").

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/f96b3b35c622d565eff2438993e028d280163f5c
• https://git.kernel.org/stable/c/6262f51e09d8dc8b07599a9e4f03bd3989d13fff
• https://git.kernel.org/stable/c/569ba39b2d12995a29dc158e5b4de6e449278f30
• https://git.kernel.org/stable/c/2b3b4e5ff5a58ad32817824b0310e63908b12052
• https://git.kernel.org/stable/c/e27beb4536cbf1d59e2d8c2840e87d972aba906f
• https://git.kernel.org/stable/c/e5824d5b841d99a2bcdd4e2c256643293bbc22c1
• https://git.kernel.org/stable/c/fe6b606fbf0c3beb94ccf17fcf31d8c2138264e3
• https://git.kernel.org/stable/c/55d9895f89970501fe126d1026b586b04a224c27