From 555041c8c2d5db324e3cb79fb65e614a4e347f64 Mon Sep 17 00:00:00 2001
From: Uri Simchoni <urisimchoni@users.noreply.github.com>
Date: Tue, 8 Aug 2017 23:38:25 +0300
Subject: [PATCH] Fix xdebug (#5309)

* [mini] fix xdebug null pointer dereferencing

Some trampolines are nameless, avoid crashing when generating their
debug info.

This change is released under the MIT license.

* [mini]: image-writer - move definition of USE_BIN_WRITER to header file

USE_BIN_WRITER is being used by xdebug for conditional compilation.

This change is released under the MIT license.

* [mini]: xdebug - obtain definition of USE_BIN_WRITER from header file

This re-enables xdebug on supported platforms.

This change is released under the MIT license.
---
 mono/mini/image-writer.c | 25 -------------------------
 mono/mini/image-writer.h | 25 +++++++++++++++++++++++++
 mono/mini/xdebug.c       | 12 +++++++++---
 3 files changed, 34 insertions(+), 28 deletions(-)

diff --git a/mono/mini/image-writer.c b/mono/mini/image-writer.c
index b5cf20dfde1..97ade6b06f1 100644
--- a/mono/mini/image-writer.c
+++ b/mono/mini/image-writer.c
@@ -120,31 +120,6 @@
 #define ALIGN_PTR_TO(ptr,align) (gpointer)((((gssize)(ptr)) + (align - 1)) & (~(align - 1)))
 #define ROUND_DOWN(VALUE,SIZE)	((VALUE) & ~((SIZE) - 1))
 
-#if defined(TARGET_AMD64) && !defined(HOST_WIN32) && !defined(__APPLE__)
-#define USE_ELF_WRITER 1
-#define USE_ELF_RELA 1
-#endif
-
-#if defined(TARGET_X86) && !defined(HOST_WIN32) && !defined(__APPLE__)
-#define USE_ELF_WRITER 1
-#endif
-
-#if defined(TARGET_ARM) && !defined(TARGET_MACH) && !defined(HOST_WIN32)
-//#define USE_ELF_WRITER 1
-#endif
-
-#if defined(__mips__)
-#define USE_ELF_WRITER 1
-#endif
-
-#if defined(TARGET_X86) && defined(__APPLE__)
-//#define USE_MACH_WRITER
-#endif
-
-#if defined(USE_ELF_WRITER) || defined(USE_MACH_WRITER)
-#define USE_BIN_WRITER 1
-#endif
-
 #ifdef USE_BIN_WRITER
 
 typedef struct _BinSymbol BinSymbol;
diff --git a/mono/mini/image-writer.h b/mono/mini/image-writer.h
index 3da1717d3e3..0c34246422e 100644
--- a/mono/mini/image-writer.h
+++ b/mono/mini/image-writer.h
@@ -22,6 +22,31 @@
 
 typedef struct _MonoImageWriter MonoImageWriter;
 
+#if defined(TARGET_AMD64) && !defined(HOST_WIN32) && !defined(__APPLE__)
+#define USE_ELF_WRITER 1
+#define USE_ELF_RELA 1
+#endif
+
+#if defined(TARGET_X86) && !defined(HOST_WIN32) && !defined(__APPLE__)
+#define USE_ELF_WRITER 1
+#endif
+
+#if defined(TARGET_ARM) && !defined(TARGET_MACH) && !defined(HOST_WIN32)
+//#define USE_ELF_WRITER 1
+#endif
+
+#if defined(__mips__)
+#define USE_ELF_WRITER 1
+#endif
+
+#if defined(TARGET_X86) && defined(__APPLE__)
+//#define USE_MACH_WRITER
+#endif
+
+#if defined(USE_ELF_WRITER) || defined(USE_MACH_WRITER)
+#define USE_BIN_WRITER 1
+#endif
+
 /* Relocation types */
 #define R_ARM_CALL 28
 #define R_ARM_JUMP24 29
diff --git a/mono/mini/xdebug.c b/mono/mini/xdebug.c
index ee8f4f79061..7d88f7da640 100644
--- a/mono/mini/xdebug.c
+++ b/mono/mini/xdebug.c
@@ -28,7 +28,6 @@
 #include <glib.h>
 #include "mini.h"
 
-#if !defined(DISABLE_AOT) && !defined(DISABLE_JIT) && USE_BIN_WRITER
 #include <sys/types.h>
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
@@ -50,6 +49,9 @@
 #include <sys/stat.h>
 
 #include "image-writer.h"
+
+#if !defined(DISABLE_AOT) && !defined(DISABLE_JIT) && USE_BIN_WRITER
+
 #include "dwarfwriter.h"
 
 #include "mono/utils/mono-compiler.h"
@@ -339,6 +341,10 @@ mono_save_xdebug_info (MonoCompile *cfg)
 void
 mono_save_trampoline_xdebug_info (MonoTrampInfo *info)
 {
+	const char *info_name = info->name;
+	if (info_name == NULL)
+		info_name = "";
+
 	if (use_gdb_interface) {
 		MonoImageWriter *w;
 		MonoDwarfWriter *dw;
@@ -348,7 +354,7 @@ mono_save_trampoline_xdebug_info (MonoTrampInfo *info)
 
 		xdebug_begin_emit (&w, &dw);
 
-		mono_dwarf_writer_emit_trampoline (dw, info->name, NULL, NULL, info->code, info->code_size, info->unwind_ops);
+		mono_dwarf_writer_emit_trampoline (dw, info_name, NULL, NULL, info->code, info->code_size, info->unwind_ops);
 
 		xdebug_end_emit (w, dw, NULL);
 		
@@ -358,7 +364,7 @@ mono_save_trampoline_xdebug_info (MonoTrampInfo *info)
 			return;
 
 		mono_loader_lock_if_inited ();
-		mono_dwarf_writer_emit_trampoline (xdebug_writer, info->name, NULL, NULL, info->code, info->code_size, info->unwind_ops);
+		mono_dwarf_writer_emit_trampoline (xdebug_writer, info_name, NULL, NULL, info->code, info->code_size, info->unwind_ops);
 		fflush (xdebug_fp);
 		mono_loader_unlock_if_inited ();
 	}
-- 
2.25.1