From: Theodore Ts'o <tytso@mit.edu>
Date: Wed, 13 Jun 2018 22:55:56 +0000 (-0400)
Subject: libext2fs: allow file systems which have insane values in s_desc_size
X-Git-Tag: v1.44.3-rc1~65
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=cedfcf2aeaee629392f04bac773d47f776ec1100;p=tools%2Fe2fsprogs.git

libext2fs: allow file systems which have insane values in s_desc_size

If the 64-bit feature is not set, the kernel does not pay attention to
the s_desc_size field in the superblock.  Change ext2fs_open2() and
other library functions to similarly ignore s_desc_size if the 64-bit
feature is not set.

The EXT2_DESC_SIZE macro should be used in most cases instead of
referecing the s_desc_size field directly.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

diff --git a/lib/ext2fs/blknum.c b/lib/ext2fs/blknum.c
index aa0e911..9ee5c66 100644
--- a/lib/ext2fs/blknum.c
+++ b/lib/ext2fs/blknum.c
@@ -208,7 +208,7 @@ __u32 ext2fs_block_bitmap_checksum(ext2_filsys fs, dgrp_t group)
 
 	gdp = ext4fs_group_desc(fs, fs->group_desc, group);
 	csum = gdp->bg_block_bitmap_csum_lo;
-	if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
+	if (EXT2_DESC_SIZE(fs->super) >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
 		csum |= ((__u32)gdp->bg_block_bitmap_csum_hi << 16);
 	return csum;
 }
@@ -249,7 +249,7 @@ __u32 ext2fs_inode_bitmap_checksum(ext2_filsys fs, dgrp_t group)
 
 	gdp = ext4fs_group_desc(fs, fs->group_desc, group);
 	csum = gdp->bg_inode_bitmap_csum_lo;
-	if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
+	if (EXT2_DESC_SIZE(fs->super) >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
 		csum |= ((__u32)gdp->bg_inode_bitmap_csum_hi << 16);
 	return csum;
 }
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index 66c41c8..9823613 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -563,7 +563,7 @@ int ext2fs_inode_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
 	provided = gdp->bg_inode_bitmap_csum_lo;
 	calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
 				      size);
-	if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
+	if (EXT2_DESC_SIZE(fs->super) >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
 		provided |= (__u32)gdp->bg_inode_bitmap_csum_hi << 16;
 	else
 		calculated &= 0xFFFF;
@@ -583,7 +583,7 @@ errcode_t ext2fs_inode_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
 
 	crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
 	gdp->bg_inode_bitmap_csum_lo = crc & 0xFFFF;
-	if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
+	if (EXT2_DESC_SIZE(fs->super) >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
 		gdp->bg_inode_bitmap_csum_hi = crc >> 16;
 
 	return 0;
@@ -601,7 +601,7 @@ int ext2fs_block_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
 	provided = gdp->bg_block_bitmap_csum_lo;
 	calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
 				      size);
-	if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
+	if (EXT2_DESC_SIZE(fs->super) >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
 		provided |= (__u32)gdp->bg_block_bitmap_csum_hi << 16;
 	else
 		calculated &= 0xFFFF;
@@ -621,7 +621,7 @@ errcode_t ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
 
 	crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
 	gdp->bg_block_bitmap_csum_lo = crc & 0xFFFF;
-	if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
+	if (EXT2_DESC_SIZE(fs->super) >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
 		gdp->bg_block_bitmap_csum_hi = crc >> 16;
 
 	return 0;
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index 532e70f..2172957 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -319,12 +319,6 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
 			retval = EXT2_ET_BAD_DESC_SIZE;
 			goto cleanup;
 		}
-	} else {
-		if (fs->super->s_desc_size &&
-		    fs->super->s_desc_size != EXT2_MIN_DESC_SIZE) {
-			retval = EXT2_ET_BAD_DESC_SIZE;
-			goto cleanup;
-		}
 	}
 
 	fs->cluster_ratio_bits = fs->super->s_log_cluster_size -