Be more restrictive about VEX prefix combinations

2019-11-02 15:53:00 +01:00
parent 5613adda25
commit c4a4df458d
1 changed files with 4 additions and 0 deletions
--- a/decode.c
+++ b/decode.c
@@ -131,6 +131,10 @@ decode_prefixes(const uint8_t* buffer, int len, DecodeMode mode,
            if (mode == DECODE_32 && (byte & 0xc0) != 0xc0)
                goto out;

+            // VEX + REX/66/F2/F3/LOCK will #UD.
+            if (prefixes & (PREFIX_REX|PREFIX_REP|PREFIX_REPNZ|PREFIX_LOCK))
+                return -1;
+
            prefixes |= PREFIX_VEX;
            prefixes |= byte & 0x80 ? 0 : PREFIX_REXR;
            if (prefix == 0xc4) // 3-byte VEX