floppy: ignore kernel-only members in FDRAWCMD ioctl input

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>

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 8f5565b..12251a6 100644 (file)
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3121,10 +3121,11 @@ 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
@@ -3140,7 +3141,6 @@ 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)