As suggested in [1], the kprobe_multi interface is to be fixed for 32-bit architectures and compat, rather then disabled. As it turned out, there are a couple of additional problems that are to be addressed: - the absence of size overflow checks, leading to possible out-of-bounds writes (addressed by the first patch); - the assumption that long has the same size as u64, which would make cookies arrays size calculation incorrect on 32-bit architectures (addressed by the second patch); - the addrs array passing API, that is incompatible with compat and has to be changed (addressed in the fourth patch): those are kernel addresses and not user ones (as was incorrectly stated in [2]); this change is only semantical for 64-bit user/kernelspace, so it shouldn't impact ABI there, at least.
[1] https://lore.kernel.org/lkml/CAADnVQ+2gwhcMht4PuDnDOFKY68Wsq8QFz4Y69NBX_TLaS... [2] https://lore.kernel.org/lkml/20220510184155.GA8295@asgard.redhat.com/
Eugene Syromiatnikov (4): bpf_trace: check size for overflow in bpf_kprobe_multi_link_attach bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach bpf_trace: handle compat in kprobe_multi_resolve_syms bpf_trace: pass array of u64 values in kprobe_multi.addrs
kernel/trace/bpf_trace.c | 63 ++++++++++++++++------ tools/lib/bpf/bpf.h | 2 +- tools/lib/bpf/libbpf.c | 8 +-- tools/lib/bpf/libbpf.h | 2 +- .../testing/selftests/bpf/prog_tests/bpf_cookie.c | 2 +- .../selftests/bpf/prog_tests/kprobe_multi_test.c | 2 +- 6 files changed, 54 insertions(+), 25 deletions(-)