[SRU][Ubuntu T, U, V, W, X] udp: properly support MSG_PEEK with truncated buffers

[Kamal Mostafa]

BugLink: http://bugs.launchpad.net/bugs/1527902
"IPv6 UDP DNS packets are not received"

[ Per Eric Dumazet: ]
  Backport of this upstream commit into stable kernels :
  89c22d8c3b27 ("net: Fix skb csum races when peeking")
  exposed a bug in udp stack vs MSG_PEEK support, when user provides a buffer
  smaller than skb payload.

Eric's patch here ("udp: properly support MSG_PEEK with truncated buffers"),
now pending in Miller's net-next queue, fixes the bug per my own testing:

  https://patchwork.ozlabs.org/patch/561746/

The patch is needed for all stable Ubuntu kernels [T, U, V, W, X].

Debian has already applied this to their 3.16.7-ckt20 based kernel:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=808293

 -Kamal

--------

Eric Dumazet (1):
  UBUNTU: SAUCE: (no-up) udp: properly support MSG_PEEK with truncated
    buffers

 net/ipv4/udp.c | 6 ++++--
 net/ipv6/udp.c | 6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

-- 
1.9.1