floppy: ignore kernel-only members in FDRAWCMD ioctl input

commit ef87dbe7614341c2e7bfe8d32fcb7028cc97442c upstream.

Always clear out these floppy_raw_cmd struct members after copying the
entire structure from userspace so that the in-kernel version is always
valid and never left in an interdeterminate state.

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

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 04ceb7e2fadd..1a8ab67d1651 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3107,10 +3107,11 @@ loop:
                 return -ENOMEM;
         *rcmd = ptr;
         ret = copy_from_user(ptr, param, sizeof(*ptr));
-        if (ret)
-                return -EFAULT;
         ptr->next = NULL;
         ptr->buffer_length = 0;
+        ptr->kernel_data = NULL;
+        if (ret)
+                return -EFAULT;
         param += sizeof(struct floppy_raw_cmd);
         if (ptr->cmd_count > 33)
                         /* the command may now also take up the space
@@ -3126,7 +3127,6 @@ loop:
         for (i = 0; i < 16; i++)
                 ptr->reply[i] = 0;
         ptr->resultcode = 0;
-        ptr->kernel_data = NULL;
 
         if (ptr->flags & (FD_RAW_READ | FD_RAW_WRITE)) {
                 if (ptr->length <= 0)