1 files changed, 13 insertions, 0 deletions

diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
index 1313ae6b478b..8f72b334aea0 100644
--- a/arch/x86/lib/insn.c
+++ b/arch/x86/lib/insn.c
@@ -52,6 +52,13 @@
  */
 void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64)
 {
+        /*
+         * Instructions longer than MAX_INSN_SIZE (15 bytes) are invalid
+         * even if the input buffer is long enough to hold them.
+         */
+        if (buf_len > MAX_INSN_SIZE)
+                buf_len = MAX_INSN_SIZE;
+
         memset(insn, 0, sizeof(*insn));
         insn->kaddr = kaddr;
         insn->end_kaddr = kaddr + buf_len;
@@ -164,6 +171,12 @@ found:
                                 /* VEX.W overrides opnd_size */
                                 insn->opnd_bytes = 8;
                 } else {
+                        /*
+                         * For VEX2, fake VEX3-like byte#2.
+                         * Makes it easier to decode vex.W, vex.vvvv,
+                         * vex.L and vex.pp. Masking with 0x7f sets vex.W == 0.
+                         */
+                        insn->vex_prefix.bytes[2] = b2 & 0x7f;
                         insn->vex_prefix.nbytes = 2;
                         insn->next_byte += 2;
                 }