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Add more precise error codes

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This commit is contained in:
Alexis Engelke
2019-11-02 22:31:10 +01:00
parent 21c40c48d0
commit dbfcf33c33
2 changed files with 31 additions and 23 deletions
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48
decode.c
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@@ -127,17 +127,17 @@ decode_prefixes(const uint8_t* buffer, int len, DecodeMode mode,
#endif
case 0xc4: case 0xc5: // VEX
if (UNLIKELY(off + 1 >= len))
return -1;
return FD_ERR_PARTIAL;
uint8_t byte = buffer[off + 1];
if (mode == DECODE_32 && (byte & 0xc0) != 0xc0)
goto out;
// VEX + 66/F2/F3/LOCK will #UD.
if (prefixes & (PREFIX_REP|PREFIX_REPNZ|PREFIX_OPSZ|PREFIX_LOCK))
return -1;
return FD_ERR_UD;
// VEX + REX will #UD.
if (rex_prefix)
return -1;
return FD_ERR_UD;
prefixes |= PREFIX_VEX;
prefixes |= byte & 0x80 ? 0 : PREFIX_REXR;
@@ -151,7 +151,7 @@ decode_prefixes(const uint8_t* buffer, int len, DecodeMode mode,
// Load third byte of VEX prefix
if (UNLIKELY(off + 2 >= len))
return -1;
return FD_ERR_PARTIAL;
byte = buffer[off + 2];
// SDM Vol 2A 2-16 (Dec. 2016) says that:
// - "In 32-bit modes, VEX.W is silently ignored."
@@ -233,7 +233,7 @@ decode_modrm(const uint8_t* buffer, int len, DecodeMode mode, FdInstr* instr,
if (rm == 4)
{
if (UNLIKELY(off >= len))
return -1;
return FD_ERR_PARTIAL;
uint8_t sib = buffer[off++];
scale = (sib & 0xc0) >> 6;
idx = (sib & 0x38) >> 3;
@@ -258,14 +258,14 @@ decode_modrm(const uint8_t* buffer, int len, DecodeMode mode, FdInstr* instr,
if (mod == 1)
{
if (UNLIKELY(off + 1 > len))
return -1;
return FD_ERR_PARTIAL;
instr->disp = (int8_t) LOAD_LE_1(&buffer[off]);
off += 1;
}
else if (mod == 2 || (mod == 0 && base == 5))
{
if (UNLIKELY(off + 4 > len))
return -1;
return FD_ERR_PARTIAL;
instr->disp = (int32_t) LOAD_LE_4(&buffer[off]);
off += 4;
}
@@ -326,7 +326,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
#endif
if (UNLIKELY(table == NULL))
return -2;
return FD_ERR_INTERNAL;
int retval;
int off = 0;
@@ -338,8 +338,10 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
retval = decode_prefixes(buffer + off, len - off, mode, &prefixes,
&mandatory_prefix, &instr->segment, &vex_operand,
&opcode_escape);
if (UNLIKELY(retval < 0 || off + retval >= len))
return -1;
if (UNLIKELY(retval < 0))
return retval;
if (UNLIKELY(off + retval >= len))
return FD_ERR_PARTIAL;
off += retval;
uint32_t kind = ENTRY_TABLE256;
@@ -360,7 +362,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
ENTRY_UNPACK(table, kind, table[buffer[off++]]);
}
else
return -1;
return FD_ERR_UD;
// Then, walk through ModR/M-encoded opcode extensions.
if ((kind == ENTRY_TABLE8 || kind == ENTRY_TABLE72) && LIKELY(off < len))
@@ -394,7 +396,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
}
else if (prefixes & PREFIX_VEX)
{
return -1;
return FD_ERR_UD;
}
if (kind == ENTRY_TABLE_PREFIX_REP)
@@ -416,7 +418,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
}
if (UNLIKELY(kind != ENTRY_INSTR))
return -1;
return FD_ERR_UD;
struct InstrDesc* desc = (struct InstrDesc*) table;
@@ -478,7 +480,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
retval = decode_modrm(buffer + off, len - off, mode, instr, prefixes,
desc->vsib, operand1, operand2);
if (UNLIKELY(retval < 0))
return -1;
return retval;
off += retval;
}
else if (DESC_HAS_MODREG(desc))
@@ -501,7 +503,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
}
else if (vex_operand != 0)
{
return -1;
return FD_ERR_UD;
}
uint32_t imm_control = DESC_IMM_CONTROL(desc);
@@ -521,7 +523,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
instr->idx_reg = FD_REG_NONE;
if (UNLIKELY(off + addr_size > len))
return -1;
return FD_ERR_PARTIAL;
#if defined(ARCH_386)
if (addr_size == 2)
instr->disp = LOAD_LE_2(&buffer[off]);
@@ -561,7 +563,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
imm_size = 4;
if (UNLIKELY(off + imm_size > len))
return -1;
return FD_ERR_PARTIAL;
if (imm_size == 1)
instr->imm = (int8_t) LOAD_LE_1(&buffer[off]);
@@ -599,16 +601,16 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
}
if ((prefixes & PREFIX_LOCK) && !desc->lock)
return -1;
return FD_ERR_UD;
if ((prefixes & PREFIX_LOCK) && instr->operands[0].type != FD_OT_MEM)
return -1;
return FD_ERR_UD;
for (int i = 0; i < 4; i++)
{
uint32_t reg_type = (desc->reg_types >> 4 * i) & 0xf;
uint32_t reg_idx = instr->operands[i].reg;
if (reg_type == FD_RT_MEM && instr->operands[i].type != FD_OT_MEM)
return -1;
return FD_ERR_UD;
if (instr->operands[i].type != FD_OT_REG)
continue;
if (reg_type == FD_RT_GPL && !(prefixes & PREFIX_REX) &&
@@ -616,14 +618,14 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
reg_type = FD_RT_GPH;
// Reject invalid segment registers
if (reg_type == FD_RT_SEG && reg_idx >= 6)
return -1;
return FD_ERR_UD;
// Reject invalid control registers
if (reg_type == FD_RT_CR && reg_idx != 0 && reg_idx != 2 &&
reg_idx != 3 && reg_idx != 4 && reg_idx != 8)
return -1;
return FD_ERR_UD;
// Reject invalid debug registers
if (reg_type == FD_RT_DR && reg_idx >= 8)
return -1;
return FD_ERR_UD;
instr->operands[i].misc = reg_type;
}