cdc-acm: hardening against malicious devices

This should fix the last holes against malicious devices
still open in cdc-acm. It cannot go into stable due to
the introduction of the common parser.
The fix for stable already merged also covers the problems this patch
fixes.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 15ffe389b86f..78f0f85bebdc 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1179,6 +1179,9 @@ static int acm_probe(struct usb_interface *intf,
                 return -EINVAL;
         }
 
+        if (!intf->cur_altsetting)
+                return -EINVAL;
+
         if (!buflen) {
                 if (intf->cur_altsetting->endpoint &&
                                 intf->cur_altsetting->endpoint->extralen &&
@@ -1232,6 +1235,8 @@ static int acm_probe(struct usb_interface *intf,
                 dev_dbg(&intf->dev, "no interfaces\n");
                 return -ENODEV;
         }
+        if (!data_interface->cur_altsetting || !control_interface->cur_altsetting)
+                return -ENODEV;
 
         if (data_intf_num != call_intf_num)
                 dev_dbg(&intf->dev, "Separate call control interface. That is not fully supported.\n");