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authorYonghong Song <yhs@fb.com>2017-11-12 14:49:10 -0800
committerDavid S. Miller <davem@davemloft.net>2017-11-14 16:20:03 +0900
commit9c019e2bc4b2bd8223c8c0d4b6962478b479834d (patch)
tree638dfe307de950e1e4101cedc34dfd82ee3dd4e1 /kernel
parent9fd29c08e52023252f0480ab8f6906a1ecc9a8d5 (diff)
download96b-common-9c019e2bc4b2bd8223c8c0d4b6962478b479834d.tar.gz
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.c8
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,
};