Hi folks, While running BPF self-tests with CONFIG_CFI_CLANG (Clang Control Flow Integrity) enabled, I ran into a couple of CFI failures in bpf_obj_free_fields() caused by type mismatches between the btf_dtor_kfunc_t function pointer type and the registered destructor functions. It looks like we can't change the argument type for these functions to match btf_dtor_kfunc_t because the verifier doesn't like void pointer arguments for functions used in BPF programs, so this series fixes the issue by adding stubs with correct types to use as destructors for each instance of this I found in the kernel tree. The last patch changes btf_check_dtor_kfuncs() to enforce the function type when CFI is enabled, so we don't end up registering destructors that panic the kernel. Perhaps this is something we could enforce even without CONFIG_CFI_CLANG? Sami --- Sami Tolvanen (4): bpf: crypto: Use the correct destructor kfunc type bpf: net_sched: Use the correct destructor kfunc type selftests/bpf: Use the correct destructor kfunc type bpf, btf: Enforce destructor kfunc type with CFI kernel/bpf/btf.c | 7 +++++++ kernel/bpf/crypto.c | 7 ++++++- net/sched/bpf_qdisc.c | 7 ++++++- tools/testing/selftests/bpf/test_kmods/bpf_testmod.c | 7 ++++++- 4 files changed, 25 insertions(+), 3 deletions(-) base-commit: 95993dc3039e29dabb9a50d074145d4cb757b08b -- 2.50.1.470.g6ba607880d-goog
