From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 6 Apr 2008 21:00:23 +0000 (-0400)
Subject: libext2fs: Fix resize inode creation with non-standard s_first_data_block
X-Git-Tag: v1.40.9~15
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=52bb0b050ab7001f92f8110c0167cedec53bdcb5;p=tools%2Fe2fsprogs.git

libext2fs: Fix resize inode creation with non-standard s_first_data_block

Thanks to Max Lindner (lokimuh) for pointing this out.

   I'm playing around a bit with ext2 and multi-user encryption and I
   need space for my key management. So I set s_first_data_block to 4000
   or something like that.

   This way mke2fs segfaults when executing
   ext2fs_create_resize_inode() because

   blk_t goal = 3 + sb->s_reserved_gdt_blocks + fs->desc_blocks +
   fs->inode_blocks_per_group;

   will produce a integer underrun later and segfault then in the
   ext2fs_test_bit assembler inline function.

   when exchanging 3 with 2 + sb->s_first_data_block, mke2fs does not
   segfault.

   I'm not 100% sure if thats the correct way dealing with this issue
   but I think its a proper solution.

Addresses-Sourceforge-Bug: #1935847

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

diff --git a/lib/ext2fs/res_gdt.c b/lib/ext2fs/res_gdt.c
index fa72fc9..ef87ab7 100644
--- a/lib/ext2fs/res_gdt.c
+++ b/lib/ext2fs/res_gdt.c
@@ -93,8 +93,9 @@ errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
 		if (retval)
 			goto out_inode;
 	} else {
-		blk_t goal = 3 + sb->s_reserved_gdt_blocks +
-			fs->desc_blocks + fs->inode_blocks_per_group;
+		blk_t goal = sb->s_first_data_block + fs->desc_blocks +
+			sb->s_reserved_gdt_blocks + 2 + 
+			fs->inode_blocks_per_group;
 
 		retval = ext2fs_alloc_block(fs, goal, 0, &dindir_blk);
 		if (retval)