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net: usb: catc: bound the RX packet length in catc_rx_done()

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catc_rx_done() walks a multi-packet URB, reading a two-byte length from
each packet header. Its bound, pkt_len > urb->actual_length, ignores the
header offset and compares against the whole transfer rather than the
bytes left from pkt_start, so a crafted packet header makes
skb_copy_to_linear_data() read past the buffer.

A length below ETH_HLEN is also accepted, including zero, and
eth_type_trans() then reads a MAC header from the uninitialised tailroom
of a shorter skb. The is_f5u011 branch takes its length straight from
the transfer, so a zero-length URB reaches the same path.

Track the bytes remaining from the current packet, and reject a header
that does not fit, a length past what is left, and a length below an
Ethernet header.

A transfer shorter than an Ethernet header, including a zero-length one,
previously became a runt skb passed to netif_rx() and counted as
received; it is now counted in rx_length_errors and ends the walk.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Aamir Ahmed <elb12345@hotmail.co.uk>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/AS8P251MB00015FD7716F38C345619B56C8BB2@AS8P251MB0001.EURP251.PROD.OUTLOOK.COM
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Aamir Ahmed 2026-09-15 00:06:58 +01:00 committed by Jakub Kicinski
parent c82b797abe
commit 9d565b6b72
1 changed files with 12 additions and 3 deletions
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15
drivers/net/usb/catc.c
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@ -233,17 +233,26 @@ static void catc_rx_done(struct urb *urb)
}
do {
if(!catc->is_f5u011) {
pkt_len = le16_to_cpup((__le16*)pkt_start);
if (pkt_len > urb->actual_length) {
int remaining = urb->actual_length -
(pkt_start - (u8 *)urb->transfer_buffer);
if (!catc->is_f5u011) {
if (remaining < pkt_offset) {
catc->netdev->stats.rx_length_errors++;
catc->netdev->stats.rx_errors++;
break;
}
pkt_len = le16_to_cpup((__le16 *)pkt_start);
} else {
pkt_len = urb->actual_length;
}
if (pkt_len < ETH_HLEN || pkt_len + pkt_offset > remaining) {
catc->netdev->stats.rx_length_errors++;
catc->netdev->stats.rx_errors++;
break;
}
if (!(skb = dev_alloc_skb(pkt_len)))
return;