[PATCH bpf v4 0/2] bpf: fix short IPv4/IPv6 handling in test_run_skb

[Sun Jian <sun.jian.kdev@gmail.com>]

bpf_prog_test_run_skb() may access IPv4/IPv6 network headers based on
skb->protocol even when the provided test input only contains an
Ethernet header.

Fix it by rejecting such short IPv4/IPv6 inputs before accessing the
L3 headers, and add a selftest that exercises the reported
bpf_skb_adjust_room() path on ETH_HLEN-sized IPv4/IPv6 EtherType
inputs.

Changes in v4:
- Split the selftests into a separate patch.
- Rework the selftest to actually execute a BPF program calling
  bpf_skb_adjust_room().
- Reuse a single struct ethhdr eth_hlen and initialize h_proto from
  the test case table.
- Add the Fixes tag to the test_run.c patch.

Link: https://lore.kernel.org/bpf/CABFUUZF_CWQZrRk=L9cNxO=8Z4iSgGfXi3J=hpzeyTKDbfE2-w@mail.gmail.com/T/#mfabfe7e86bb30c0141fbc9f751b8b1cb07767f01

Sun Jian (2):
  bpf: reject short IPv4/IPv6 inputs in bpf_prog_test_run_skb
  selftests/bpf: cover short IPv4/IPv6 inputs with adjust_room

 net/bpf/test_run.c                            | 20 ++++++----
 .../selftests/bpf/prog_tests/empty_skb.c      | 40 +++++++++++++++++--
 tools/testing/selftests/bpf/progs/empty_skb.c |  7 ++++
 3 files changed, 56 insertions(+), 11 deletions(-)


base-commit: cbfffcca2bf0622b601b7eaf477aa29035169184
-- 
2.43.0