Instead of always emitting BPF_REG_X, let's emit BPF_REG_X only when the
source actually is BPF_X. This causes programs generated by the classic
converter to not be importable via bpf(), as the eBPF verifier checks that
the src_reg is correct or 0. While not a problem yet, this will be a
problem when BPF_PROG_DUMP lands, and we can potentially dump and re-import
programs generated by the converter.
Signed-off-by: Tycho Andersen <tycho.ander...@canonical.com>
CC: Alexei Starovoitov <a...@kernel.org>
CC: Daniel Borkmann <dan...@iogearbox.net>
---
net/core/filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 13079f0..05a04ea 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -478,9 +478,9 @@ do_pass:
bpf_src = BPF_X;
} else {
insn->dst_reg = BPF_REG_A;
- insn->src_reg = BPF_REG_X;
insn->imm = fp->k;
bpf_src = BPF_SRC(fp->code);
+ insn->src_reg = bpf_src == BPF_X ? BPF_REG_X :
0;
}
/* Common case where 'jump_false' is next insn. */
--
2.1.4
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