[ Upstream commit c7ca03c216 ]
1. Added a skb->len check
This driver expects upper layers to include a pseudo header of 1 byte
when passing down a skb for transmission. This driver will read this
1-byte header. This patch added a skb->len check before reading the
header to make sure the header exists.
2. Changed to use needed_headroom instead of hard_header_len to request
necessary headroom to be allocated
In net/packet/af_packet.c, the function packet_snd first reserves a
headroom of length (dev->hard_header_len + dev->needed_headroom).
Then if the socket is a SOCK_DGRAM socket, it calls dev_hard_header,
which calls dev->header_ops->create, to create the link layer header.
If the socket is a SOCK_RAW socket, it "un-reserves" a headroom of
length (dev->hard_header_len), and assumes the user to provide the
appropriate link layer header.
So according to the logic of af_packet.c, dev->hard_header_len should
be the length of the header that would be created by
dev->header_ops->create.
However, this driver doesn't provide dev->header_ops, so logically
dev->hard_header_len should be 0.
So we should use dev->needed_headroom instead of dev->hard_header_len
to request necessary headroom to be allocated.
This change fixes kernel panic when this driver is used with AF_PACKET
SOCK_RAW sockets.
Call stack when panic:
[ 168.399197] skbuff: skb_under_panic: text:ffffffff819d95fb len:20
put:14 head:ffff8882704c0a00 data:ffff8882704c09fd tail:0x11 end:0xc0
dev:veth0
...
[ 168.399255] Call Trace:
[ 168.399259] skb_push.cold+0x14/0x24
[ 168.399262] eth_header+0x2b/0xc0
[ 168.399267] lapbeth_data_transmit+0x9a/0xb0 [lapbether]
[ 168.399275] lapb_data_transmit+0x22/0x2c [lapb]
[ 168.399277] lapb_transmit_buffer+0x71/0xb0 [lapb]
[ 168.399279] lapb_kick+0xe3/0x1c0 [lapb]
[ 168.399281] lapb_data_request+0x76/0xc0 [lapb]
[ 168.399283] lapbeth_xmit+0x56/0x90 [lapbether]
[ 168.399286] dev_hard_start_xmit+0x91/0x1f0
[ 168.399289] ? irq_init_percpu_irqstack+0xc0/0x100
[ 168.399291] __dev_queue_xmit+0x721/0x8e0
[ 168.399295] ? packet_parse_headers.isra.0+0xd2/0x110
[ 168.399297] dev_queue_xmit+0x10/0x20
[ 168.399298] packet_sendmsg+0xbf0/0x19b0
......
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Martin Schiller <ms@dev.tdt.de>
Cc: Brian Norris <briannorris@chromium.org>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
f6c5d9f336