USB: usbfs: only copy the actual data received

commit d4a4683ca054ed9917dfc9e3ff0f7ecf74ad90d6 upstream.

We need to only copy the data received by the device to userspace, not
the whole kernel buffer, which can contain "stale" data.

Thanks to Marcus Meissner for pointing this out and testing the fix.

Reported-by: Marcus Meissner <meissner@suse.de>
Tested-by: Marcus Meissner <meissner@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 181f78c84105c090df4689b44845638472ccb8ef..bff195859e14cac5212ae0cec40dc7278989f5f7 100644 (file)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1312,9 +1312,9 @@ static int processcompl(struct async *as, void __user * __user *arg)
        void __user *addr = as->userurb;
        unsigned int i;
 
-       if (as->userbuffer)
+       if (as->userbuffer && urb->actual_length)
                if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-                                urb->transfer_buffer_length))
+                                urb->actual_length))
                        goto err_out;
        if (put_user(as->status, &userurb->status))
                goto err_out;
@@ -1435,9 +1435,9 @@ static int processcompl_compat(struct async *as, void __user * __user *arg)
        void __user *addr = as->userurb;
        unsigned int i;
 
-       if (as->userbuffer)
+       if (as->userbuffer && urb->actual_length)
                if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-                                urb->transfer_buffer_length))
+                                urb->actual_length))
                        return -EFAULT;
        if (put_user(as->status, &userurb->status))
                return -EFAULT;