dm table: fail dm_table_create on dm_round_up overflow

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>
Cc: stable@vger.kernel.org

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 465f08ca62b1e355f8fd776fac4a6159d79a1a2e..3ba6a3859ce3c4957439ff3afdc4a5133bc2900b 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -200,6 +200,11 @@ 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;