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>
(cherry picked from commit 2145e15e)
Signed-off-by: Willy Tarreau <w@1wt.eu>

drivers/block/floppy.c

@@ -3162,7 +3162,12 @@ static inline int raw_cmd_copyout(int cmd, char __user *param,
 	int ret;
 
 	while (ptr) {
-		COPYOUT(*ptr);
+		struct floppy_raw_cmd cmd = *ptr;
+		cmd.next = NULL;
+		cmd.kernel_data = NULL;
+		ret = copy_to_user((void __user *)param, &cmd, sizeof(cmd));
+		if (ret)
+			return -EFAULT;
 		param += sizeof(struct floppy_raw_cmd);
 		if ((ptr->flags & FD_RAW_READ) && ptr->buffer_length) {
 			if (ptr->length >= 0