[PATCH net 0/3] rtnetlink: fix silent truncation when first dump entry does not fit

[Stephen Hemminger <stephen@networkplumber.org>]

While analyzing one of the OSS Scanner dump reports for iproute2,
a bug was uncovered in netlink route dump.
A route dump whose first entry is too large for the dump skb ends with
NLMSG_DONE and status 0. The route and everything after it is silently
dropped; "ip route show table 100" prints nothing and exits 0 even
though "ip route get" still finds the route. A 500 way multipath route
is enough to trigger this.

The series is broken into three parts:
  1. Fix regression in rtnl_dumpit().
     Do not hide EMSGSIZE on empty skb case.
  2. Fix IPv6 FIB dump to propagate error properly
  3. Add a test for this bug.

Stephen Hemminger (3):
  rtnetlink: return EMSGSIZE when first dump entry does not fit
  ipv6: return EMSGSIZE when first route in dump does not fit
  selftests: net: netlink-dumps: test dump of route larger than skb

 net/core/rtnetlink.c                        |   5 +-
 net/ipv6/ip6_fib.c                          |   6 +
 tools/testing/selftests/net/config          |   3 +
 tools/testing/selftests/net/netlink-dumps.c | 271 +++++++++++++++++++-
 4 files changed, 280 insertions(+), 5 deletions(-)

-- 
2.53.0