linux-kernel - [PATCH 3.2 116/125] target: Explicitly clear ramdisk

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Message-ID: <lsq.1404846110.610641042@decadent.org.uk>
Date:	Tue, 08 Jul 2014 20:01:50 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Nicholas Bellinger" <nab@...ux-iscsi.org>,
	"Jorge Daniel Sequeira Matias" <jdsm@...nico.ulisboa.pt>
Subject: [PATCH 3.2 116/125] target: Explicitly clear ramdisk_mcp backend
 pages

3.2.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nicholas Bellinger <nab@...ux-iscsi.org>

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@...nico.ulisboa.pt>
Cc: Jorge Daniel Sequeira Matias <jdsm@...nico.ulisboa.pt>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/target/target_core_rd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- 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
 						- 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");

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