Zheng Lv <lv.zheng.2015@xxxxxxxxx> writes:
> The original code did not check for size of device. A truncated device
> would mount, I/O failures would occur when "attempt to access beyond end
> of device", leading to data lost.
>
> Fix this by comparing total-sectors field in BPB with size of device.
>
> This commit also prints a KERN_INFO message if there are extra sectors
> at end of device (ie. total sectors < device sectors).
[...]
> + device_sectors = sb->s_bdev->bd_inode->i_size / logical_sector_size;
> + if (device_sectors && total_sectors > device_sectors) {
> + fat_msg(sb, KERN_ERR, "total sectors %u "
> + "exceeds size of device (%llu sectors)",
> + total_sectors, device_sectors);
> + goto out_invalid;
Hm, it is a bit hard to think what to do. But I guess it is better to
allow access to rescue some files. (Yes, it may lost new data. But
read-only or in-place update is safe.)
> + } else if (device_sectors && total_sectors < device_sectors) {
> + fat_msg(sb, KERN_INFO, "%llu unused sectors at end of device",
> + device_sectors - total_sectors);
This is legal setup. So, probably, should not pollute log for each mount.
> + }
> +
> total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
>
> if (sbi->fat_bits != 32)
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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