From febbc583319b567fe3d83e521cc2ace9be8d1501 Mon Sep 17 00:00:00 2001
From: Benjamin Lim <jarsp.ctf@gmail.com>
Date: Fri, 29 Mar 2019 07:29:45 -0400
Subject: [PATCH] Fix ext4 block group descriptor sizing
Ext4 allows for arbitrarily sized block group descriptors when 64-bit
addressing is enabled, which was previously not properly supported. This
patch dynamically allocates a chunk of memory of the correct size.
Signed-off-by: Benjamin Lim <jarsp.ctf@gmail.com>
Signed-off-by Ajay Kaher <akaher@vmware.com?
---
fs/ext4/ext4_common.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index feffbfa..464c33d 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -1587,7 +1587,7 @@ static int ext4fs_blockgroup
int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
{
- struct ext2_block_group blkgrp;
+ struct ext2_block_group *blkgrp;
struct ext2_sblock *sblock = &data->sblock;
struct ext_filesystem *fs = get_fs();
int log2blksz = get_fs()->dev_desc->log2blksz;
@@ -1595,17 +1595,28 @@ int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
long int blkno;
unsigned int blkoff;
+ /* Allocate blkgrp based on gdsize (for 64-bit support). */
+ blkgrp = zalloc(get_fs()->gdsize);
+ if (!blkgrp)
+ return 0;
+
/* It is easier to calculate if the first inode is 0. */
ino--;
status = ext4fs_blockgroup(data, ino / le32_to_cpu
- (sblock->inodes_per_group), &blkgrp);
- if (status == 0)
+ (sblock->inodes_per_group), blkgrp);
+ if (status == 0) {
+ free(blkgrp);
return 0;
+ }
inodes_per_block = EXT2_BLOCK_SIZE(data) / fs->inodesz;
- blkno = ext4fs_bg_get_inode_table_id(&blkgrp, fs) +
+ blkno = ext4fs_bg_get_inode_table_id(blkgrp, fs) +
(ino % le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
blkoff = (ino % inodes_per_block) * fs->inodesz;
+
+ /* Free blkgrp as it is no longer required. */
+ free(blkgrp);
+
/* Read the inode. */
status = ext4fs_devread((lbaint_t)blkno << (LOG2_BLOCK_SIZE(data) -
log2blksz), blkoff,
--
2.7.4