Commit a03ffcf8 authored Dec 17, 2011 by Markus Kötter Committed by David S. Miller Dec 19, 2011

net: bpf_jit: fix an off-one bug in x86_64 cond jump target



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 <nepenthesdev@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent d1388dac

arch/x86/net/bpf_jit_comp.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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);