CVE-2026-31616 PUBLISHED

usb: gadget: f_phonet: fix skb frags[] overflow in pn_rx_complete()

Assigner: Linux
Reserved: 09.03.2026 Published: 24.04.2026 Updated: 25.04.2026

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").

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from b91cd1440870f7a0649e570498b7b93caf9f781c to c9315ce9da3632c591666a29de82d3e92d46bec1 (excl.)
  • affected from b91cd1440870f7a0649e570498b7b93caf9f781c to 4e476c25bfcab0535ba7c76a903ae77ca8747711 (excl.)
  • affected from b91cd1440870f7a0649e570498b7b93caf9f781c to bd44ce09b9b569f49ed13e2d87d23d853fc7d6a7 (excl.)
  • affected from b91cd1440870f7a0649e570498b7b93caf9f781c to 66f7471c4042e4eb300e30b5b9d87d1406862673 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 2.6.32 is affected
  • unaffected from 0 to 2.6.32 (excl.)
  • unaffected from 6.12.83 to 6.12.* (incl.)
  • unaffected from 6.18.24 to 6.18.* (incl.)
  • unaffected from 6.19.14 to 6.19.* (incl.)
  • unaffected from 7.0.1 to 7.0.* (incl.)

References