dm table: fail dm_table_create on dm_round_up overflow

commit 5b2d06576c5410c10d95adfd5c4d8b24de861d87 upstream.

The dm_round_up function may overflow to zero.  In this case,
dm_table_create() must fail rather than go on to allocate an empty array
with alloc_targets().

This fixes a possible memory corruption that could be caused by passing
too large a number in "param->target_count".

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 9e3a045eb7a2..bd88d3dade1e 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -215,6 +215,11 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
 
         num_targets = dm_round_up(num_targets, KEYS_PER_NODE);
 
+        if (!num_targets) {
+                kfree(t);
+                return -ENOMEM;
+        }
+
         if (alloc_targets(t, num_targets)) {
                 kfree(t);
                 return -ENOMEM;