[systemd-devel] Crash and size problem with systemd-repart

[Emmanuel Garette]

Hi,

I'm experimenting with the new tool systemd-repart and I think I have 
found a bug.

Here is a simple repart.d file:

     bash-5.0# cat /usr/lib/repart.d/70-home.conf
     [Partition]
     Type=home
     SizeMinBytes=16M
     SizeMaxBytes=32M

If the disk is empty, systemd-repart ends with a segfault: 
https://github.com/systemd/systemd/issues/15608

So a create a new partition on the disk:

     bash-5.0# parted /dev/sdb
     (parted) print
     Model: ATA VBOX HARDDISK (scsi)
     Disk /dev/sdb: 32.2GB
     Sector size (logical/physical): 512B/512B
     Partition Table: gpt
     Disk Flags:

     Number  Start   End    Size   File system  Name     Flags
      1      1049kB  322MB  321MB               primary

And I run systemd-repart:

     bash-5.0# systemd-repart /dev/sdb --dry-run=no
     TYPE          LABEL   UUID FILE              NODE SIZE       PADDING
     home          home    af89e705-7395-4f23-8261-2f7229fc506b 
70-home.conf /dev/sdb2 -> 306.0M  -> 0B
     linux-generic primary fe7a74f4-8827-4233-94ac-0adbf8e3704d 
-            /dev/sdb1 306.0M     29.6G -> 29.4G
S = 612.0M S = 29.4G

X---------------------------------------------------------------------------------------------------------------------------XX
      `- primary |
`- 70-home.conf

     Applying changes.
     Storage does not support discarding, not discarding data in new 
partition 1.
     Successfully wiped file system signatures from partition 1.
     Storage does not support discarding, not discarding gap at 
beginning of disk.
     Creating new partition 1.
     Writing new partition table.
     Telling kernel to reread partition table.
     All done.

As you can see, there is a problem with the partition's size: 300MB 
instead of 32MB max.

Parted confirm:

     Number  Start   End     Size   File system  Name     Flags
      1      1049kB  322MB   321MB               primary
      2      31.9GB  32.2GB  321MB               home

I think the problem is here in src/partition/repart.c:

           /* What? Even still some space left (maybe because there was 
no preceding partition, or it had   a
            * size limit), then let's donate it to whoever wants it. */
           if (span > 0) {
                   Partition *p;

                   LIST_FOREACH(partitions, p, context->partitions) {
                           uint64_t m, xsz;

                           if (p->allocated_to_area != a)
                                   continue;

                           if (PARTITION_IS_FOREIGN(p))
                                   continue;

                           assert(p->new_size != UINT64_MAX);
                           m = p->new_size + span;

                           xsz = partition_max_size(a->after);
                           if (xsz != UINT64_MAX && m > xsz)
                                   m = xsz;

                           span = charge_size(span, m - p->new_size);
                           p->new_size = m;

                           if (span == 0)
                                   break;
                   }
           }


The problem is in line "xsz = partition_max_size(a->after);"

xsz is the max size of "a->after" instead current partition (so "p").

Am I right? I'll make a PR if yes.

Regards,

-- 
Emmanuel Garette
  Ingénieur en informatique libre
  
  Cadoles (http://www.cadoles.com)
  Experts EOLE, Envole et logiciels libres

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