CVE-2026-31616

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_phonet: fix skb frags[] overflow in pn_rx_complete() A broken/bored/mean USB host can overflow the skb_shared_info->frags[] array on a Linux gadget exposing a Phonet function by sending an unbounded sequence of full-page OUT transfers. pn_rx_complete() finalizes the skb only when req->actual < req->length, where req->length is set to PAGE_SIZE by the gadget. If the host always sends exactly PAGE_SIZE bytes per transfer, fp->rx.skb will never be reset and each completion will add another fragment via skb_add_rx_frag(). Once nr_frags exceeds MAX_SKB_FRAGS (default 17), subsequent frag stores overwrite memory adjacent to the shinfo on the heap. Drop the skb and account a length error when the frag limit is reached, matching the fix applied in t7xx by commit f0813bcd2d9d ("net: wwan: t7xx: fix potential skb->frags overflow in RX path").

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://git.kernel.org/stable/c/4e476c25bfcab0535ba7c76a903ae77ca8747711
• https://git.kernel.org/stable/c/66f7471c4042e4eb300e30b5b9d87d1406862673
• https://git.kernel.org/stable/c/9ceff1251904901b0b4e5fe6350fcaffa368ce83
• https://git.kernel.org/stable/c/bd44ce09b9b569f49ed13e2d87d23d853fc7d6a7
• https://git.kernel.org/stable/c/c088d5dd2fffb4de1fb8e7f57751c8b82942180a
• https://git.kernel.org/stable/c/c9315ce9da3632c591666a29de82d3e92d46bec1
• https://www.suse.com/security/cve/CVE-2026-31616.html
• https://security-tracker.debian.org/tracker/CVE-2026-31616

CWEs

CWE-401