From 8370e6efa974f560e7b69c0f60544a7368e74547 Mon Sep 17 00:00:00 2001
From: Peter Johnson <peter@tortall.net>
Date: Mon, 10 Dec 2007 05:20:32 +0000
Subject: [PATCH] Fix NULL dereference for certain cases of REX used with jump
 instruction.

svn path=/trunk/yasm/; revision=2024
---
 modules/arch/x86/tests/Makefile.inc    | 3 +++
 modules/arch/x86/tests/o64loop.asm     | 3 +++
 modules/arch/x86/tests/o64loop.errwarn | 1 +
 modules/arch/x86/tests/o64loop.hex     | 2 ++
 modules/arch/x86/x86bc.c               | 5 ++++-
 5 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 modules/arch/x86/tests/o64loop.asm
 create mode 100644 modules/arch/x86/tests/o64loop.errwarn
 create mode 100644 modules/arch/x86/tests/o64loop.hex

diff --git a/modules/arch/x86/tests/Makefile.inc b/modules/arch/x86/tests/Makefile.inc
index c9093246..9069d2c2 100644
--- a/modules/arch/x86/tests/Makefile.inc
+++ b/modules/arch/x86/tests/Makefile.inc
@@ -104,6 +104,9 @@ EXTRA_DIST += modules/arch/x86/tests/nomem64.errwarn
 EXTRA_DIST += modules/arch/x86/tests/nomem64.hex
 EXTRA_DIST += modules/arch/x86/tests/o64.asm
 EXTRA_DIST += modules/arch/x86/tests/o64.hex
+EXTRA_DIST += modules/arch/x86/tests/o64loop.asm
+EXTRA_DIST += modules/arch/x86/tests/o64loop.errwarn
+EXTRA_DIST += modules/arch/x86/tests/o64loop.hex
 EXTRA_DIST += modules/arch/x86/tests/opersize.asm
 EXTRA_DIST += modules/arch/x86/tests/opersize.hex
 EXTRA_DIST += modules/arch/x86/tests/opsize-err.asm
diff --git a/modules/arch/x86/tests/o64loop.asm b/modules/arch/x86/tests/o64loop.asm
new file mode 100644
index 00000000..14f7951b
--- /dev/null
+++ b/modules/arch/x86/tests/o64loop.asm
@@ -0,0 +1,3 @@
+[bits 64]
+o64 loop next
+next:
diff --git a/modules/arch/x86/tests/o64loop.errwarn b/modules/arch/x86/tests/o64loop.errwarn
new file mode 100644
index 00000000..55f8201b
--- /dev/null
+++ b/modules/arch/x86/tests/o64loop.errwarn
@@ -0,0 +1 @@
+-:2: warning: ignoring REX prefix on jump
diff --git a/modules/arch/x86/tests/o64loop.hex b/modules/arch/x86/tests/o64loop.hex
new file mode 100644
index 00000000..55e2c214
--- /dev/null
+++ b/modules/arch/x86/tests/o64loop.hex
@@ -0,0 +1,2 @@
+e2 
+00 
diff --git a/modules/arch/x86/x86bc.c b/modules/arch/x86/x86bc.c
index f3717bf7..dfcaa26c 100644
--- a/modules/arch/x86/x86bc.c
+++ b/modules/arch/x86/x86bc.c
@@ -294,7 +294,10 @@ yasm_x86__bc_apply_prefixes(x86_common *common, unsigned char *rex,
                 common->opersize = (unsigned char)prefixes[i] & 0xff;
                 if (common->mode_bits == 64 && common->opersize == 64 &&
                     def_opersize_64 != 64) {
-                    if (*rex == 0xff)
+                    if (!rex)
+                        yasm_warn_set(YASM_WARN_GENERAL,
+                                      N_("ignoring REX prefix on jump"));
+                    else if (*rex == 0xff)
                         yasm_warn_set(YASM_WARN_GENERAL,
                             N_("REX prefix not allowed on this instruction, ignoring"));
                     else
-- 
2.40.0