From: Jan Kara jack@suse.cz
commit d766f2d1e3e3bd44024a7f971ffcf8b8fbb7c5d2 upstream.
Add sanity check that filesystem size does not exceed the underlying device size and that group size is big enough so that metadata can fit into it. This avoid trying to mount some crafted filesystems with extremely large group counts.
Reported-by: syzbot+0f2f7e65a3007d39539f@syzkaller.appspotmail.com Reported-by: kernel test robot oliver.sang@intel.com # Test fixup CC: stable@vger.kernel.org Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext2/super.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
--- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -1052,6 +1052,13 @@ static int ext2_fill_super(struct super_ sbi->s_blocks_per_group); goto failed_mount; } + /* At least inode table, bitmaps, and sb have to fit in one group */ + if (sbi->s_blocks_per_group <= sbi->s_itb_per_group + 3) { + ext2_msg(sb, KERN_ERR, + "error: #blocks per group smaller than metadata size: %lu <= %lu", + sbi->s_blocks_per_group, sbi->s_inodes_per_group + 3); + goto failed_mount; + } if (sbi->s_frags_per_group > sb->s_blocksize * 8) { ext2_msg(sb, KERN_ERR, "error: #fragments per group too big: %lu", @@ -1065,9 +1072,14 @@ static int ext2_fill_super(struct super_ sbi->s_inodes_per_group); goto failed_mount; } + if (sb_bdev_nr_blocks(sb) < le32_to_cpu(es->s_blocks_count)) { + ext2_msg(sb, KERN_ERR, + "bad geometry: block count %u exceeds size of device (%u blocks)", + le32_to_cpu(es->s_blocks_count), + (unsigned)sb_bdev_nr_blocks(sb)); + goto failed_mount; + }
- if (EXT2_BLOCKS_PER_GROUP(sb) == 0) - goto cantfind_ext2; sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) - le32_to_cpu(es->s_first_data_block) - 1) / EXT2_BLOCKS_PER_GROUP(sb)) + 1;