1 files changed, 33 insertions, 8 deletions

diff --git a/fs/squashfs/export.c b/fs/squashfs/export.c
index ae2c87bb0fbe..eb02072d28dd 100644
--- a/fs/squashfs/export.c
+++ b/fs/squashfs/export.c
@@ -41,12 +41,17 @@ static long long squashfs_inode_lookup(struct super_block *sb, int ino_num)
 	struct squashfs_sb_info *msblk = sb->s_fs_info;
 	int blk = SQUASHFS_LOOKUP_BLOCK(ino_num - 1);
 	int offset = SQUASHFS_LOOKUP_BLOCK_OFFSET(ino_num - 1);
-	u64 start = le64_to_cpu(msblk->inode_lookup_table[blk]);
+	u64 start;
 	__le64 ino;
 	int err;
 
 	TRACE("Entered squashfs_inode_lookup, inode_number = %d\n", ino_num);
 
+	if (ino_num == 0 || (ino_num - 1) >= msblk->inodes)
+		return -EINVAL;
+
+	start = le64_to_cpu(msblk->inode_lookup_table[blk]);
+
 	err = squashfs_read_metadata(sb, &ino, &start, &offset, sizeof(ino));
 	if (err < 0)
 		return err;
@@ -111,7 +116,10 @@ __le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
 		u64 lookup_table_start, u64 next_table, unsigned int inodes)
 {
 	unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
+	unsigned int indexes = SQUASHFS_LOOKUP_BLOCKS(inodes);
+	int n;
 	__le64 *table;
+	u64 start, end;
 
 	TRACE("In read_inode_lookup_table, length %d\n", length);
 
@@ -121,20 +129,37 @@ __le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
 	if (inodes == 0)
 		return ERR_PTR(-EINVAL);
 
-	/* length bytes should not extend into the next table - this check
-	 * also traps instances where lookup_table_start is incorrectly larger
-	 * than the next table start
+	/*
+	 * The computed size of the lookup table (length bytes) should exactly
+	 * match the table start and end points
 	 */
-	if (lookup_table_start + length > next_table)
+	if (length != (next_table - lookup_table_start))
 		return ERR_PTR(-EINVAL);
 
 	table = squashfs_read_table(sb, lookup_table_start, length);
+	if (IS_ERR(table))
+		return table;
 
 	/*
-	 * table[0] points to the first inode lookup table metadata block,
-	 * this should be less than lookup_table_start
+	 * table0], table[1], ... table[indexes - 1] store the locations
+	 * of the compressed inode lookup blocks.  Each entry should be
+	 * less than the next (i.e. table[0] < table[1]), and the difference
+	 * between them should be SQUASHFS_METADATA_SIZE or less.
+	 * table[indexes - 1] should  be less than lookup_table_start, and
+	 * again the difference should be SQUASHFS_METADATA_SIZE or less
 	 */
-	if (!IS_ERR(table) && le64_to_cpu(table[0]) >= lookup_table_start) {
+	for (n = 0; n < (indexes - 1); n++) {
+		start = le64_to_cpu(table[n]);
+		end = le64_to_cpu(table[n + 1]);
+
+		if (start >= end || (end - start) > SQUASHFS_METADATA_SIZE) {
+			kfree(table);
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	start = le64_to_cpu(table[indexes - 1]);
+	if (start >= lookup_table_start || (lookup_table_start - start) > SQUASHFS_METADATA_SIZE) {
 		kfree(table);
 		return ERR_PTR(-EINVAL);
 	}