From 0f9d5dc758113fafd82e2deb56b2805938155132 Mon Sep 17 00:00:00 2001 From: Neel Natu Date: Tue, 17 Sep 2013 16:06:07 +0000 Subject: [PATCH] Fix a bug in decoding an instruction that has an SIB byte as well as an immediate operand. The presence of an SIB byte in decoding the ModR/M field would cause 'imm_bytes' to not be set to the correct value. Fix this by initializing 'imm_bytes' independent of the ModR/M decoding. Reported by: grehan@ Approved by: re@ --- sys/amd64/vmm/vmm_instruction_emul.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/sys/amd64/vmm/vmm_instruction_emul.c b/sys/amd64/vmm/vmm_instruction_emul.c index 4af22d478e0f..94aa49267763 100644 --- a/sys/amd64/vmm/vmm_instruction_emul.c +++ b/sys/amd64/vmm/vmm_instruction_emul.c @@ -701,12 +701,6 @@ decode_modrm(struct vie *vie) break; } - /* Figure out immediate operand size (if any) */ - if (vie->op.op_flags & VIE_OP_F_IMM) - vie->imm_bytes = 4; - else if (vie->op.op_flags & VIE_OP_F_IMM8) - vie->imm_bytes = 1; - done: vie_advance(vie); @@ -822,6 +816,12 @@ decode_immediate(struct vie *vie) int32_t signed32; } u; + /* Figure out immediate operand size (if any) */ + if (vie->op.op_flags & VIE_OP_F_IMM) + vie->imm_bytes = 4; + else if (vie->op.op_flags & VIE_OP_F_IMM8) + vie->imm_bytes = 1; + if ((n = vie->imm_bytes) == 0) return (0);