[PATCH bpf-next 0/2] Avoid dummy bpf_offload_netdev in __bpf_prog_dev_bound_init

[Eduard Zingerman <eddyz87@gmail.com>]

For a device bound BPF program with flag BPF_F_XDP_DEV_BOUND_ONLY,
in case if device does not support offload, __bpf_prog_dev_bound_init()
creates a dummy bpf_offload_netdev struct with .offdev field set to NULL.

This dummy struct might be reused for programs without this flag
bound to the same device. However, bpf_prog_offload_verifier_prep()
that uses bpf_offload_netdev assumes that .offdev field cannot be NULL.

This bug was reported by syzbot in [1].

[1] https://lore.kernel.org/bpf/000000000000d97f3c060479c4f8@google.com/

Eduard Zingerman (2):
  bpf: Avoid dummy bpf_offload_netdev in __bpf_prog_dev_bound_init
  selftests/bpf: Offloaded prog after non-offloaded should not cause BUG

 kernel/bpf/offload.c                          | 12 ++--
 .../bpf/prog_tests/xdp_dev_bound_only.c       | 58 +++++++++++++++++++
 2 files changed, 65 insertions(+), 5 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_dev_bound_only.c

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2.41.0