block/compat_ioctl.c: do not leak info to user-space

There is a hole in struct hd_geometry, so we have to zero the struct on
stack before copying it to user-space.

Signed-off-by: Cong Wang <amwang@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 7c668c8a6f95..7e5d474dc6ba 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -59,6 +59,7 @@ static int compat_hdio_getgeo(struct gendisk *disk, struct block_device *bdev,
         if (!disk->fops->getgeo)
                 return -ENOTTY;
 
+        memset(&geo, 0, sizeof(geo));
         /*
          * We need to set the startsect first, the driver may
          * want to override it.