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Date: Thu, 10 Sep 2015 18:25:07 -0600 From: Tycho Andersen <tycho.andersen@...onical.com> To: Alexei Starovoitov <ast@...nel.org>, "David S. Miller" <davem@...emloft.net> Cc: netdev@...r.kernel.org, Tycho Andersen <tycho.andersen@...onical.com>, Daniel Borkmann <daniel@...earbox.net> Subject: [PATCH] ebpf: emit correct src_reg for conditional jumps 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.andersen@...onical.com> CC: Alexei Starovoitov <ast@...nel.org> CC: Daniel Borkmann <daniel@...earbox.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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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