The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 12cb908a11b2544b5f53e9af856e6b6a90ed5533 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Date: Thu, 3 Dec 2020 13:50:50 +0900
Subject: [PATCH] x86/insn-eval: Use new for_each_insn_prefix() macro to loop
over prefixes bytes
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
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;
