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>

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index d509f236bd542f74047d6832c1a50f79080ddd4c..43e19b76af8c1e1ed4a718996d131414d094d462 100644 (file)
--- 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);
                t = NULL;