Right now, there is no safe way to use BPF_PROG_TEST_RUN with data_out. This is because bpf_test_finish copies the output buffer to user space without checking its size. This can lead to the kernel overwriting data in user space after the buffer if xdp_adjust_head and friends are in play.
Changes in v3: * Introduce bpf_prog_test_run_xattr instead of modifying the existing function Changes in v2: * Make the syscall return ENOSPC if data_size_out is too small * Make bpf_prog_test_run return EINVAL if size_out is missing * Document the new behaviour of data_size_out Lorenz Bauer (4): bpf: respect size hint to BPF_PROG_TEST_RUN if present tools: sync uapi/linux/bpf.h libbpf: add bpf_prog_test_run_xattr selftests: add a test for bpf_prog_test_run_xattr include/uapi/linux/bpf.h | 7 +++- net/bpf/test_run.c | 15 +++++++- tools/include/uapi/linux/bpf.h | 7 +++- tools/lib/bpf/bpf.c | 27 +++++++++++++ tools/lib/bpf/bpf.h | 13 +++++++ tools/testing/selftests/bpf/test_progs.c | 49 ++++++++++++++++++++++++ 6 files changed, 112 insertions(+), 6 deletions(-) -- 2.17.1
