From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
commit 12cb908a11b2544b5f53e9af856e6b6a90ed5533 upstream
Since insn.prefixes.nbytes can be bigger than the size of
insn.prefixes.bytes[] when a prefix is repeated, the proper check must
be
insn.prefixes.bytes[i] != 0 and i < 4
instead of using insn.prefixes.nbytes. Use the new
for_each_insn_prefix() macro which does it correctly.
Debugged by Kees Cook <keescook@xxxxxxxxxxxx>.
[ bp: Massage commit message. ]
Fixes: 32d0b95300db ("x86/insn-eval: Add utility functions to get segment selector")
Reported-by: syzbot+9b64b619f10f19d19a7c@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/160697104969.3146288.16329307586428270032.stgit@devnote2
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/lib/insn-eval.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -70,14 +70,15 @@ static int get_seg_reg_override_idx(stru
{
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;
