linux-kernel - [PATCH bpf 0/4] Fix 32-bit arch and compat support for the kprobe

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Date:   Mon, 16 May 2022 20:26:57 +0200
From:   Eugene Syromiatnikov <esyr@...hat.com>
To:     Jiri Olsa <jolsa@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Cc:     Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org
Subject: [PATCH bpf 0/4] Fix 32-bit arch and compat support for the
 kprobe_multi attach type

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_TLaSexQQ@mail.gmail.com/
[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(-)

-- 
2.1.4