diff options
author | iximeow <me@iximeow.net> | 2020-11-19 18:13:24 -0800 |
---|---|---|
committer | iximeow <me@iximeow.net> | 2020-11-19 18:13:24 -0800 |
commit | 81e9b93aab9217cf7cb508f64b19fc1c0df024b5 (patch) | |
tree | 4a17eed4bd3191d3f02417d6c7d63420a474fb95 /src | |
parent | e3a400b7a96284d1394cd710ea3bcee01dbfe95f (diff) |
fix decoding of rex-prefixed modrm+sib operands selecting index 0b100 and base 0b1010.1.4
for memory operands with a base, index, and displacement either
the wrong base would be selected (register number ignored, so only
`*ax` or `r8*` would be reported), or yaxpeax-x86 would report a
base register is present when it is not (`RegIndexBaseScaleDisp`
when the operand is actually `RegScaleDisp`)
thank you to Evan Johnson for catching and reporting this bug!
also bump crate version to 0.1.4 as this will be immediately tagged and
released.
Diffstat (limited to 'src')
-rw-r--r-- | src/long_mode/mod.rs | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/src/long_mode/mod.rs b/src/long_mode/mod.rs index 363c605..d165e38 100644 --- a/src/long_mode/mod.rs +++ b/src/long_mode/mod.rs @@ -5665,20 +5665,28 @@ fn read_sib<T: Iterator<Item=u8>>(bytes_iter: &mut T, instr: &mut Instruction, m OperandSpec::DispU32 } else { + instr.modrm_mmm.num |= 0b101; + if instr.prefixes.rex().x() { instr.sib_index.num = 0b1100; let scale = 1u8 << (sibbyte >> 6); instr.scale = scale; if disp == 0 { - OperandSpec::RegIndexBaseScale + if modbits == 0 { + OperandSpec::RegScale + } else { + OperandSpec::RegIndexBaseScale + } } else { instr.disp = disp as i64 as u64; - OperandSpec::RegIndexBaseScaleDisp + if modbits == 0 { + OperandSpec::RegScaleDisp + } else { + OperandSpec::RegIndexBaseScaleDisp + } } } else { - instr.modrm_mmm.num |= 0b101; - if disp == 0 { OperandSpec::Deref } else { |