FAILED: patch "[PATCH] x86/insn-eval: Use new for_each_insn_prefix() macro to loop" failed to apply to 5.9-stable tree

The patch below does not apply to the 5.9-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 <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 12cb908a11b2544b5f53e9af856e6b6a90ed5533 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <[email protected]>
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 <[email protected]>.

[ bp: Massage commit message. ]

index 58f7fb95c7f4..4229950a5d78 100644
@@ -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;

Hi Greg,

Here is the backport. Will apply to all branches till 4.19-stable.

--
Regards
Sudip

From 948726feb2ca94059d75f09ee5b4f78343f9d2d8 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <[email protected]>
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

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 <[email protected]>.

[ bp: Massage commit message. ]

---
 arch/x86/lib/insn-eval.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index 5e69603ff63f..694f32845116 100644
@@ -70,14 +70,15 @@ 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;

2.11.0

Thanks, now queued up!

greg k-h