libblkid: avoid non-empty recursion in EBR

This is extension to the patch 7164a1c34d18831ac61c6744ad14ce916d389b3f.

We also need to detect non-empty recursion in the EBR chain. It's
possible to create standard valid logical partitions and in the last one
points back to the EBR chain. In this case all offsets will be non-empty.

Unfortunately, it's valid to create logical partitions that are not in
the "disk order" (sorted by start offset). So link somewhere back is
valid, but this link cannot points to already existing partition
(otherwise we will see recursion).

This patch forces libblkid to ignore duplicate logical partitions, the
duplicate chain segment is interpreted as non-data segment, after 100
iterations with non-data segments it will break the loop -- no memory
is allocated in this case by the loop.

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1349536
References: http://seclists.org/oss-sec/2016/q3/40
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libblkid/src/partitions/dos.c b/libblkid/src/partitions/dos.c
index e79f124f830e489acfa379835fc176c6664ebda5..2a6414025950e379a2054cee07db0e156bd6ff21 100644 (file)
--- a/libblkid/src/partitions/dos.c
+++ b/libblkid/src/partitions/dos.c
@@ -105,6 +105,13 @@ static int parse_dos_extended(blkid_probe pr, blkid_parttable tab,
                                        continue;
                        }
 
+                       /* Avoid recursive non-empty links, see ct_nodata counter */
+                       if (blkid_partlist_get_partition_by_start(ls, abs_start)) {
+                               DBG(LOWPROBE, ul_debug("#%d: EBR duplicate data partition [abs start=%u] -- ignore",
+                                                       i + 1, abs_start));
+                               continue;
+                       }
+
                        par = blkid_partlist_add_partition(ls, tab, abs_start, size);
                        if (!par)
                                return -ENOMEM;

diff --git a/libblkid/src/partitions/partitions.c b/libblkid/src/partitions/partitions.c
index 806fced80c04c47276b675ed6e4169b65fdfb40f..533209761cfdd79951d32f4d02fd05c6b279bada 100644 (file)
--- a/libblkid/src/partitions/partitions.c
+++ b/libblkid/src/partitions/partitions.c
@@ -935,6 +935,20 @@ blkid_partition blkid_partlist_get_partition(blkid_partlist ls, int n)
        return &ls->parts[n];
 }
 
+blkid_partition blkid_partlist_get_partition_by_start(blkid_partlist ls, uint64_t start)
+{
+       int i, nparts;
+       blkid_partition par;
+
+       nparts = blkid_partlist_numof_partitions(ls);
+       for (i = 0; i < nparts; i++) {
+               par = blkid_partlist_get_partition(ls, i);
+               if ((uint64_t) blkid_partition_get_start(par) == start)
+                       return par;
+       }
+       return NULL;
+}
+
 /**
  * blkid_partlist_get_partition_by_partno
  * @ls: partitions list

diff --git a/libblkid/src/partitions/partitions.h b/libblkid/src/partitions/partitions.h
index 7ec03b21ddbf6bd1836b78bb2ec44f3972d83869..1d99fb6a36e56f0444ec4d6df9bac9ad9e9d263f 100644 (file)
--- a/libblkid/src/partitions/partitions.h
+++ b/libblkid/src/partitions/partitions.h
@@ -21,6 +21,8 @@ extern int blkid_partlist_increment_partno(blkid_partlist ls);
 
 extern blkid_partition blkid_partlist_get_parent(blkid_partlist ls);
 
+extern blkid_partition blkid_partlist_get_partition_by_start(blkid_partlist ls, uint64_t start);
+
 extern int blkid_partitions_do_subprobe(blkid_probe pr,
                        blkid_partition parent, const struct blkid_idinfo *id);