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

[Kamal Mostafa]

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-3.8.y-queue branch of the 3.8.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-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.16.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 17655bf4edb9f45c5b89eecb74f5b61ec68068b9 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: Kamal Mostafa <kamal 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 ee51e08..f5e5ed5 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