floppy: don't write kernel-only members to FDRAWCMD ioctl output

Do not leak kernel-only floppy_raw_cmd structure members to userspace.
This includes the linked-list pointer and the pointer to the allocated
DMA space.

Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 12251a688871..fa9bb742df6e 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3067,7 +3067,10 @@ static int raw_cmd_copyout(int cmd, void __user *param,
         int ret;
 
         while (ptr) {
-                ret = copy_to_user(param, ptr, sizeof(*ptr));
+                struct floppy_raw_cmd cmd = *ptr;
+                cmd.next = NULL;
+                cmd.kernel_data = NULL;
+                ret = copy_to_user(param, &cmd, sizeof(cmd));
                 if (ret)
                         return -EFAULT;
                 param += sizeof(struct floppy_raw_cmd);