From: Mikulas Patocka <mpatocka@redhat.com>
Date: Sat, 23 Nov 2013 00:52:06 +0000 (-0500)
Subject: dm table: fail dm_table_create on dm_round_up overflow
X-Git-Url: http://git.mmlx.us/?a=commitdiff_plain;h=135949c10b4f97eaf9da90535e18c6a2a0e2993a;p=linux-edison.git

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 9e3a045eb7a..bd88d3dade1 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;