Since the insn.prefixes.nbytes can be bigger than the size of
insn.prefixes.bytes[] when a same prefix is repeated, we have to
check whether the insn.prefixes.bytes[i] != 0 and i < 4 instead
of insn.prefixes.nbytes.

Fixes: 32d0b95300db ("x86/insn-eval: Add utility functions to get segment 
selector")
Reported-by: [email protected]
Debugged-by: Kees Cook <[email protected]>
Signed-off-by: Masami Hiramatsu <[email protected]>
Cc: [email protected]
---
 arch/x86/lib/insn-eval.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index 58f7fb95c7f4..4229950a5d78 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -63,13 +63,12 @@ static bool is_string_insn(struct insn *insn)
  */
 bool insn_has_rep_prefix(struct insn *insn)
 {
+       insn_byte_t p;
        int i;
 
        insn_get_prefixes(insn);
 
-       for (i = 0; i < insn->prefixes.nbytes; i++) {
-               insn_byte_t p = insn->prefixes.bytes[i];
-
+       for_each_insn_prefix(insn, i, p) {
                if (p == 0xf2 || p == 0xf3)
                        return true;
        }
@@ -95,14 +94,15 @@ static int get_seg_reg_override_idx(struct insn *insn)
 {
        int idx = INAT_SEG_REG_DEFAULT;
        int num_overrides = 0, i;
+       insn_byte_t p;
 
        insn_get_prefixes(insn);
 
        /* Look for any segment override prefixes. */
-       for (i = 0; i < insn->prefixes.nbytes; i++) {
+       for_each_insn_prefix(insn, i, p) {
                insn_attr_t attr;
 
-               attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]);
+               attr = inat_get_opcode_attribute(p);
                switch (attr) {
                case INAT_MAKE_PREFIX(INAT_PFX_CS):
                        idx = INAT_SEG_REG_CS;

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