Merge branch 'net-skb_put_padto-fixes'

Eric Dumazet says:

====================
net: skb_put_padto() fixes

sysbot reported a bug in qrtr leading to use-after-free.

First patch fixes the issue.

Second patch addes __must_check attribute to avoid similar
issues in the future.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>