From 0fa24fd72d32468ce796d8d560bca6b07c3476ca Mon Sep 17 00:00:00 2001
From: dev747368 <48332326+dev747368@users.noreply.github.com>
Date: Tue, 22 Jun 2021 18:57:40 -0400
Subject: [PATCH] GP-1067 fix Ext4 mounting fs in an oversized volume

The fs mounting code was using the physical volume size instead of
values from the superblock.
---
 .../file/formats/ext4/Ext4FileSystem.java     | 22 +++++++------------
 .../formats/ext4/Ext4GroupDescriptor.java     |  8 +++++++
 .../file/formats/ext4/Ext4SuperBlock.java     |  8 +++++++
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4FileSystem.java b/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4FileSystem.java
index 2bc33985d7..5d6f9f0a0b 100644
--- a/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4FileSystem.java
+++ b/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4FileSystem.java
@@ -57,15 +57,13 @@ public class Ext4FileSystem implements GFileSystem {
 
 		this.uuid = NumericUtilities.convertBytesToString(superBlock.getS_uuid());
 
+		long blockCount = superBlock.getS_blocks_count();
+
 		int s_log_block_size = superBlock.getS_log_block_size();
 		blockSize = (int) Math.pow(2, (10 + s_log_block_size));
 
-		int groupSize = blockSize * superBlock.getS_blocks_per_group();
-		if (groupSize <= 0) {
-			throw new IOException("Invalid groupSize: " + groupSize);
-		}
-		int numGroups = (int) (provider.length() / groupSize);
-		if (provider.length() % groupSize != 0) {
+		int numGroups = (int) (blockCount / superBlock.getS_blocks_per_group());
+		if (blockCount % superBlock.getS_blocks_per_group() != 0) {
 			numGroups++;
 		}
 
@@ -81,7 +79,7 @@ public class Ext4FileSystem implements GFileSystem {
 			monitor.incrementProgress(1);
 		}
 
-		Ext4Inode[] inodes = getInodes(reader, superBlock, groupDescriptors, is64Bit, monitor);
+		Ext4Inode[] inodes = getInodes(reader, superBlock, groupDescriptors, monitor);
 
 		int s_inodes_count = superBlock.getS_inodes_count();
 		for (int i = 0; i < s_inodes_count; i++) {
@@ -400,23 +398,19 @@ public class Ext4FileSystem implements GFileSystem {
 	}
 
 	private Ext4Inode[] getInodes(BinaryReader reader, Ext4SuperBlock superBlock,
-			Ext4GroupDescriptor[] groupDescriptors, boolean is64Bit, TaskMonitor monitor)
+			Ext4GroupDescriptor[] groupDescriptors, TaskMonitor monitor)
 			throws IOException, CancelledException {
 
 		int inodeCount = superBlock.getS_inodes_count();
+		int inodesPerGroup = superBlock.getS_inodes_per_group();
 		Ext4Inode[] inodes = new Ext4Inode[inodeCount + 1];
 		int inodeIndex = 1;
 
 		for (int i = 0; i < groupDescriptors.length; i++) {
 			monitor.checkCanceled();
-			long inodeTableBlockOffset = groupDescriptors[i].getBg_inode_table_lo() & 0xffffffffL;
-			if (is64Bit) {
-				inodeTableBlockOffset =
-					(groupDescriptors[i].getBg_inode_table_hi() << 32) | inodeTableBlockOffset;
-			}
+			long inodeTableBlockOffset = groupDescriptors[i].getBg_inode_table();
 			long offset = inodeTableBlockOffset * blockSize;
 			reader.setPointerIndex(offset);
-			int inodesPerGroup = superBlock.getS_inodes_per_group();
 			monitor.setMessage(
 				"Reading inode table " + i + " of " + (groupDescriptors.length - 1) + "...");
 			monitor.setMaximum(inodesPerGroup);
diff --git a/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4GroupDescriptor.java b/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4GroupDescriptor.java
index 53a2090a43..df69b75bfe 100644
--- a/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4GroupDescriptor.java
+++ b/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4GroupDescriptor.java
@@ -149,6 +149,14 @@ public class Ext4GroupDescriptor implements StructConverter {
 		return bg_inode_table_hi;
 	}
 
+	/**
+	 * Return the calculated inode table value by combining bg_inode_table_lo and bg_inode_table_hi
+	 * @return the calculated inode table value by combining bg_inode_table_lo and bg_inode_table_hi
+	 */
+	public long getBg_inode_table() {
+		return ((long) bg_inode_table_hi << 32) | Integer.toUnsignedLong(bg_inode_table_lo);
+	}
+
 	public short getBg_free_blocks_count_hi() {
 		return bg_free_blocks_count_hi;
 	}
diff --git a/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4SuperBlock.java b/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4SuperBlock.java
index d2a7e4b7d6..cb20ba2544 100644
--- a/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4SuperBlock.java
+++ b/Ghidra/Features/FileFormats/src/main/java/ghidra/file/formats/ext4/Ext4SuperBlock.java
@@ -226,6 +226,14 @@ public class Ext4SuperBlock implements StructConverter {
 		return s_blocks_count_lo;
 	}
 
+	/**
+	 * Return the calculated block count by combining the s_blocks_count_lo and s_blocks_count_hi
+	 * @return the calculated block count by combining the s_blocks_count_lo and s_blocks_count_hi
+	 */
+	public long getS_blocks_count() {
+		return ((long) s_blocks_count_hi << 32) | Integer.toUnsignedLong(s_blocks_count_lo);
+	}
+
 	public int getS_r_blocks_count_lo() {
 		return s_r_blocks_count_lo;
 	}