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 33b29350586ded019c45ef29094970e05364af1e..4151f9f17eec5a8a55d97da92a28ef855507dbf1 100644 (file)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1224,9 +1224,9 @@ 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;
@@ -1347,9 +1347,9 @@ 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;