diff options
| author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-07 11:55:05 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-07 14:50:34 +0300 |
| commit | c088d5dd2fffb4de1fb8e7f57751c8b82942180a (patch) | |
| tree | f421007cbdccf7856cecbdb480bfc0d0e2351e15 | |
| parent | 2c863dbbeac7b919d4634ad886978a6731916de3 (diff) | |
| download | linux-c088d5dd2fffb4de1fb8e7f57751c8b82942180a.tar.xz | |
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").
Cc: stable <stable@kernel.org>
Assisted-by: gregkh_clanker_t1000
Link: https://patch.msgid.link/2026040705-fruit-unloved-0701@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/gadget/function/f_phonet.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/usb/gadget/function/f_phonet.c b/drivers/usb/gadget/function/f_phonet.c index 2c007790ead2..b1ee9a7c2e94 100644 --- a/drivers/usb/gadget/function/f_phonet.c +++ b/drivers/usb/gadget/function/f_phonet.c @@ -333,6 +333,15 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req) if (unlikely(!skb)) break; + if (unlikely(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS)) { + /* Frame count from host exceeds frags[] capacity */ + dev_kfree_skb_any(skb); + if (fp->rx.skb == skb) + fp->rx.skb = NULL; + dev->stats.rx_length_errors++; + break; + } + if (skb->len == 0) { /* First fragment */ skb->protocol = htons(ETH_P_PHONET); skb_reset_mac_header(skb); |