[3.11.y.z extended stable] Patch "target: Explicitly clear ramdisk_mcp backend pages" has been added to staging queue

[Luis Henriques]

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

    target: Explicitly clear ramdisk_mcp backend pages

to the linux-3.11.y-queue branch of the 3.11.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-3.11.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 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From c4f6762165301b5354dcb1062ebfe1408c089a6b Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab at linux-iscsi.org>
Date: Mon, 16 Jun 2014 20:59:52 +0000
Subject: target: Explicitly clear ramdisk_mcp backend pages

This patch changes rd_allocate_sgl_table() to explicitly clear
ramdisk_mcp backend memory pages by passing __GFP_ZERO into
alloc_pages().

This addresses a potential security issue where reading from a
ramdisk_mcp could return sensitive information, and follows what
>= v3.15 does to explicitly clear ramdisk_mcp memory at backend
device initialization time.

[ Note that a different patch to address the same issue went in during
  v3.15-rc1 (commit 4442dc8a), but includes a bunch of other changes that
  don't strictly apply to fixing the bug.

  This is a one-liner that addresses the bug for all <= v3.14 versions. ]

Reported-by: Jorge Daniel Sequeira Matias <jdsm at tecnico.ulisboa.pt>
Cc: Jorge Daniel Sequeira Matias <jdsm at tecnico.ulisboa.pt>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/target/target_core_rd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 51127d15d5c5..d71cdbed413b 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -179,7 +179,7 @@ static int rd_build_device_space(struct rd_dev *rd_dev)
 						- 1;

 		for (j = 0; j < sg_per_table; j++) {
-			pg = alloc_pages(GFP_KERNEL, 0);
+			pg = alloc_pages(GFP_KERNEL | __GFP_ZERO, 0);
 			if (!pg) {
 				pr_err("Unable to allocate scatterlist"
 					" pages for struct rd_dev_sg_table\n");
--
1.9.1