[3.5.y.z extended stable] Patch "dm table: fail dm_table_create on dm_round_up overflow" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    dm table: fail dm_table_create on dm_round_up overflow

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 2e132ec1f820ef0fc5ca16ecf307f1eb8509005a Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka at redhat.com>
Date: Fri, 22 Nov 2013 19:52:06 -0500
Subject: 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 at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/md/dm-table.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index d509f23..43e19b7 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);
 		t = NULL;
--
1.8.3.2