From a03ffcf873fe0f2565386ca8ef832144c42e67fa Mon Sep 17 00:00:00 2001 From: =?utf8?q?Markus=20K=C3=B6tter?= Date: Sat, 17 Dec 2011 11:39:08 +0000 Subject: [PATCH] net: bpf_jit: fix an off-one bug in x86_64 cond jump target MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit x86 jump instruction size is 2 or 5 bytes (near/long jump), not 2 or 6 bytes. In case a conditional jump is followed by a long jump, conditional jump target is one byte past the start of target instruction. Signed-off-by: Markus Kötter Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- arch/x86/net/bpf_jit_comp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index bfab3fa..7b65f75 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -568,8 +568,8 @@ cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i]; break; } if (filter[i].jt != 0) { - if (filter[i].jf) - t_offset += is_near(f_offset) ? 2 : 6; + if (filter[i].jf && f_offset) + t_offset += is_near(f_offset) ? 2 : 5; EMIT_COND_JMP(t_op, t_offset); if (filter[i].jf) EMIT_JMP(f_offset); -- 2.7.4