From: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Mon, 16 Jun 2014 20:59:52 +0000 (+0000)
Subject: target: Explicitly clear ramdisk_mcp backend pages
X-Git-Tag: v3.2.61~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bbe9504c3a9f7cea3cd6d2660142d9b9bd5821f7;p=pandora-kernel.git

target: Explicitly clear ramdisk_mcp backend pages

Part of commit 4442dc8a92b8f9ad8ee9e7f8438f4c04c03a22dc upstream.

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.

Reported-by: Jorge Daniel Sequeira Matias <jdsm@tecnico.ulisboa.pt>
Cc: Jorge Daniel Sequeira Matias <jdsm@tecnico.ulisboa.pt>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 02e51faa2f4e..6c7886b1b683 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");