On 14/05/2018 3:20 AM, David Miller wrote:
From: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Date: Fri, 11 May 2018 13:24:25 -0400
From: Willem de Bruijn <will...@google.com>
Packet sockets allow construction of packets shorter than
dev->hard_header_len to accommodate protocols with variable length
link layer headers. These packets are padded to dev->hard_header_len,
because some device drivers interpret that as a minimum packet size.
packet_snd reserves dev->hard_header_len bytes on allocation.
SOCK_DGRAM sockets call skb_push in dev_hard_header() to ensure that
link layer headers are stored in the reserved range. SOCK_RAW sockets
do the same in tpacket_snd, but not in packet_snd.
Syzbot was able to send a zero byte packet to a device with massive
116B link layer header, causing padding to cross over into skb_shinfo.
Fix this by writing from the start of the llheader reserved range also
in the case of packet_snd/SOCK_RAW.
Update skb_set_network_header to the new offset. This also corrects
it for SOCK_DGRAM, where it incorrectly double counted reserve due to
the skb_push in dev_hard_header.
Fixes: 9ed988cd5915 ("packet: validate variable length ll headers")
Reported-by: syzbot+71d74a5406d02057d...@syzkaller.appspotmail.com
Signed-off-by: Willem de Bruijn <will...@google.com>
Applied and queued up for -stable, thanks Willem.
Hi,
One of our regression tests started failing. Once this patch is
reverted, test passes.
The tests add flow steering rules in the receiver side and in the sender
side it send the packet with some RAW socket applications. Then received
side gets completion with error.
Our verification team compared the packets between the stable and the
broken version, in the broken version we have some extra bytes at the
end of the packet.
It looks like some bad push to the SKB, maybe the conditional reserved
addition should be more strict?
Any idea?
Regards,
Tariq
