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

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: 1da177e4c3f4 ("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>

0 files changed, 0 insertions, 0 deletions