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

commit 2145e15e0557a01b9195d1c7199a1b92cb9be81f upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 56490fe..6d0f3e1 100644 (file)
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3060,7 +3060,10 @@ 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);