]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
dccp: limit sk_filter trim to payload
authorWillem de Bruijn <willemb@google.com>
Tue, 12 Jul 2016 22:18:57 +0000 (18:18 -0400)
committerDavid S. Miller <davem@davemloft.net>
Wed, 13 Jul 2016 18:53:41 +0000 (11:53 -0700)
commit4f0c40d94461cfd23893a17335b2ab78ecb333c8
treebb43f8374b6e157c5a412b30d2e528a808939067
parentf4979fcea7fd36d8e2f556abef86f80e0d5af1ba
dccp: limit sk_filter trim to payload

Dccp verifies packet integrity, including length, at initial rcv in
dccp_invalid_packet, later pulls headers in dccp_enqueue_skb.

A call to sk_filter in-between can cause __skb_pull to wrap skb->len.
skb_copy_datagram_msg interprets this as a negative value, so
(correctly) fails with EFAULT. The negative length is reported in
ioctl SIOCINQ or possibly in a DCCP_WARN in dccp_close.

Introduce an sk_receive_skb variant that caps how small a filter
program can trim packets, and call this in dccp with the header
length. Excessively trimmed packets are now processed normally and
queued for reception as 0B payloads.

Fixes: 7c657876b63c ("[DCCP]: Initial implementation")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/sock.h
net/core/sock.c
net/dccp/ipv4.c
net/dccp/ipv6.c