block: ioctl: fix information leak to userland
Structure hd_geometry is copied to userland with 4 padding bytes
between cylinders and start fields uninitialized on 64-bit platforms.
It leads to leaking of contents of kernel stack memory.
Currently there is no memset() in real implementations of getgeo()
in drivers/block/, so it makes sense to have memset() in blkdev_ioctl().
Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/block/ioctl.c b/block/ioctl.c
index 38aa194..3d866d0 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -242,6 +242,7 @@
* We need to set the startsect first, the driver may
* want to override it.
*/
+ memset(&geo, 0, sizeof(geo));
geo.start = get_start_sect(bdev);
ret = disk->fops->getgeo(bdev, &geo);
if (ret)