ISDN: hfcsusb: checking idx of ep configuration

commit f384e62a82ba5d85408405fdd6aeff89354deaa9 upstream.

The syzbot test with random endpoint address which made the idx is
overflow in the table of endpoint configuations.

this adds the checking for fixing the error report from
syzbot

KASAN: stack-out-of-bounds Read in hfcsusb_probe [1]
The patch tested by syzbot [2]

Reported-by: syzbot+8750abbc3a46ef47d509@syzkaller.appspotmail.com
[1]:
https://syzkaller.appspot.com/bug?id=30a04378dac680c5d521304a00a86156bb913522
[2]:
https://groups.google.com/d/msg/syzkaller-bugs/_6HBdge8F3E/OJn7wVNpBAAJ

Signed-off-by: Phong Tran <tranmanphong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index 17cc879ad2bbf784be196528d14a533bf0267b29..35983c7c313754d0e37410ec826b1a3d1aa33410 100644 (file)
--- a/drivers/isdn/hardware/mISDN/hfcsusb.c
+++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
@@ -1963,6 +1963,9 @@ hfcsusb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
                                /* get endpoint base */
                                idx = ((ep_addr & 0x7f) - 1) * 2;
+                               if (idx > 15)
+                                       return -EIO;
+
                                if (ep_addr & 0x80)
                                        idx++;
                                attr = ep->desc.bmAttributes;