ping: prevent NULL pointer dereference on write to msg_name

A plain read() on a socket does set msg->msg_name to NULL. So check for
NULL pointer first.

[Backport of net-next cf970c002d270c36202bd5b9c2804d3097a52da0]

Bug: 12780426
Change-Id: I29d9cb95ef05ec76d37517e01317f4a29e60931c
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
netfilter: xt_IDLETIMER: Revert to retain the kernel API format.

Reverted Change-Id: Iaeca5dd2d7878c0733923ae03309a2a7b86979ca

Change-Id: I0e0a4f60ec14330d8d8d1c5a508fa058d9919e07
Signed-off-by: Ashish Sharma <ashishsharma@google.com>
fix false disconnect due to a signal sent to the reading process

- In the current implementation, when a signal is sent to the reading process,
  read is cancelled by calling usb_ep_dequeue, which lead into calling
  acc_complete_out with ECONNRESET, but the current logic treats it as
  disconnection, which makes the device inaccessible until cable is actually
  disconnected.
- The fix calls disconnect only when ESHUTDOWN error is passed.
- If data has already arrived while trying cancelling, the data is marked
  as available, and it will be read out on the next read. This is necessary
  as USB bulk is assumed to guarantee no data loss.

Change-Id: I97132d819ff37a2805ab4a74779ee59ef3944139
Signed-off-by: keunyoung <keunyoung@google.com>
tcp: add a sysctl to config the tcp_default_init_rwnd

The default initial rwnd was hardcoded to 10.

Now we allow it to be controlled via
  /proc/sys/net/ipv4/tcp_default_init_rwnd
which limits the values from 3 to 100

This is somewhat needed because ipv6 routes are
autoconfigured by the kernel.

See "An Argument for Increasing TCP's Initial Congestion Window"
in https://developers.google.com/speed/articles/tcp_initcwnd_paper.pdf

Signed-off-by: JP Abgrall <jpa@google.com>

Change-Id: Ib2d21ceae130d0bed676ae2d2c7d29e12a6cb299