Commit 9378c676 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o

ext4: fix overflow when updating superblock backups after resize

When there are no meta block groups update_backups() will compute the
backup block in 32-bit arithmetics thus possibly overflowing the block
number and corrupting the filesystem. OTOH filesystems without meta
block groups larger than 16 TB should be rare. Fix the problem by doing
the counting in 64-bit arithmetics.

Coverity-id: 741252
CC: stable@vger.kernel.org
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarLukas Czerner <lczerner@redhat.com>
parent cac7f242
...@@ -1081,7 +1081,7 @@ static void update_backups(struct super_block *sb, int blk_off, char *data, ...@@ -1081,7 +1081,7 @@ static void update_backups(struct super_block *sb, int blk_off, char *data,
break; break;
if (meta_bg == 0) if (meta_bg == 0)
backup_block = group * bpg + blk_off; backup_block = ((ext4_fsblk_t)group) * bpg + blk_off;
else else
backup_block = (ext4_group_first_block_no(sb, group) + backup_block = (ext4_group_first_block_no(sb, group) +
ext4_bg_has_super(sb, group)); ext4_bg_has_super(sb, group));
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment