linux-kernel - [PATCH 3.4 31/43] [PATCH] target: Explicitly clear ramdisk

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Message-Id: <20140628174451.217186940@linuxfoundation.org>
Date:	Sat, 28 Jun 2014 10:46:22 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org,
	target-devel <target-devel@...r.kernel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Jorge Daniel Sequeira Matias <jdsm@...nico.ulisboa.pt>,
	Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [PATCH 3.4 31/43] [PATCH] target: Explicitly clear ramdisk_mcp backend pages

3.4-stable review patch.  If anyone has any objections, please let me know.

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


[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 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: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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
@@ -177,7 +177,7 @@ 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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