[PATCH 3.2 116/125] target: Explicitly clear ramdisk_mcp backend pages

From: Ben Hutchings
Date: Tue Jul 08 2014 - 15:44:30 EST

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


From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

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

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@xxxxxxxxxxxxxxxxxx>
Cc: Jorge Daniel Sequeira Matias <jdsm@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
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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