From d3a380992541537b16cf5cf1d117ddf3427bbfbc Mon Sep 17 00:00:00 2001
From: emteere <47253321+emteere@users.noreply.github.com>
Date: Fri, 3 Dec 2021 23:06:45 +0000
Subject: [PATCH] GP-1575_emteere code review

---
 .../gcc/AbstractDwarfEHDecoder.java                  | 12 +++++++-----
 .../exceptionhandlers/gcc/DwarfDecodeContext.java    | 12 ++++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/AbstractDwarfEHDecoder.java b/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/AbstractDwarfEHDecoder.java
index 30e0cdb0a1..1d0298a2e5 100644
--- a/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/AbstractDwarfEHDecoder.java
+++ b/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/AbstractDwarfEHDecoder.java
@@ -17,7 +17,6 @@ package ghidra.app.plugin.exceptionhandlers.gcc;
 
 import ghidra.app.plugin.exceptionhandlers.gcc.datatype.SignedLeb128DataType;
 import ghidra.app.plugin.exceptionhandlers.gcc.datatype.UnsignedLeb128DataType;
-import ghidra.app.util.opinion.ElfLoader;
 import ghidra.program.model.address.*;
 import ghidra.program.model.data.*;
 import ghidra.program.model.listing.Program;
@@ -334,10 +333,13 @@ abstract class AbstractDwarfEHDecoder implements DwarfEHDecoder {
 
 		switch (appMode) {
 			case DW_EH_PE_absptr:
-				// if the program has been rebased, need to add in the image base difference.
-				Long oib = ElfLoader.getElfOriginalImageBase(prog);
-				long programBaseAddressFixup = prog.getImageBase().getOffset() - oib.longValue();
-				val = val + programBaseAddressFixup;
+				// if the program has been re-based, need to add in the image base difference.
+				//  but only if there are no relocations at this location
+				if (prog.getRelocationTable().getRelocation(addr) == null) {
+					long programBaseAddressFixup = context.getOriginalImageBaseOffset();
+
+					val = val + programBaseAddressFixup;
+				}
 				break;
 
 			case DW_EH_PE_aligned:
diff --git a/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/DwarfDecodeContext.java b/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/DwarfDecodeContext.java
index e4177210af..6357323392 100644
--- a/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/DwarfDecodeContext.java
+++ b/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/exceptionhandlers/gcc/DwarfDecodeContext.java
@@ -15,6 +15,7 @@
  */
 package ghidra.app.plugin.exceptionhandlers.gcc;
 
+import ghidra.app.util.opinion.ElfLoader;
 import ghidra.program.model.address.Address;
 import ghidra.program.model.listing.Function;
 import ghidra.program.model.listing.Program;
@@ -34,6 +35,7 @@ public class DwarfDecodeContext {
 	private Object decodedValue;
 	private int encodedLength;
 	private MemBuffer buffer;
+	private long originalImageBaseOffset;  // offset from image base used in original dwarf, and the actual load image base
 
 	/**
 	 * Constructs a Dwarf decode context.
@@ -96,6 +98,8 @@ public class DwarfDecodeContext {
 		this.ehBlock = ehBlock;
 		this.functionEntryPoint = entryPoint;
 
+		Long oib = ElfLoader.getElfOriginalImageBase(program);
+		this.originalImageBaseOffset = program.getImageBase().getOffset() - oib.longValue();
 	}
 
 	/**
@@ -180,4 +184,12 @@ public class DwarfDecodeContext {
 	public Address getFunctionEntryPoint() {
 		return functionEntryPoint;
 	}
+
+	/**
+	 * Gets the offset from the programs image base and the dwarf original image base
+	 * @return offset that if added to the current image base would be the original dwarf image base
+	 */
+	public long getOriginalImageBaseOffset() {
+		return originalImageBaseOffset;
+	}
 }