diff options
| author |   Yonghong Song <yhs@fb.com> | 2017-11-12 14:49:10 -0800 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-11-14 16:20:03 +0900 |
| commit | 9c019e2bc4b2bd8223c8c0d4b6962478b479834d (patch) | |
| tree | 638dfe307de950e1e4101cedc34dfd82ee3dd4e1 /kernel | |
| parent | bpf: improve verifier ARG_CONST_SIZE_OR_ZERO semantics (diff) | |
| download | linux-dev-9c019e2bc4b2bd8223c8c0d4b6962478b479834d.tar.xz linux-dev-9c019e2bc4b2bd8223c8c0d4b6962478b479834d.zip | |
bpf: change helper bpf_probe_read arg2 type to ARG_CONST_SIZE_OR_ZERO
The helper bpf_probe_read arg2 type is changed
from ARG_CONST_SIZE to ARG_CONST_SIZE_OR_ZERO to permit
size-0 buffer. Together with newer ARG_CONST_SIZE_OR_ZERO
semantics which allows non-NULL buffer with size 0,
this allows simpler bpf programs with verifier acceptance.
The previous commit which changes ARG_CONST_SIZE_OR_ZERO semantics
has details on examples.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/bpf_trace.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 506efe6e8ed9..a5580c670866 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -78,12 +78,16 @@ EXPORT_SYMBOL_GPL(trace_call_bpf); BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr) { - int ret; + int ret = 0; + + if (unlikely(size == 0)) + goto out; ret = probe_kernel_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) memset(dst, 0, size); + out: return ret; } @@ -92,7 +96,7 @@ static const struct bpf_func_proto bpf_probe_read_proto = { .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_UNINIT_MEM, - .arg2_type = ARG_CONST_SIZE, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, .arg3_type = ARG_ANYTHING, }; |