From 5dfdd24eb3d39d815bc952ae98128e967c9bba49 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Tue, 21 Aug 2018 11:59:53 +0200
Subject: [PATCH] USB: serial: ti_usb_3410_5052: fix array underflow in completion handler
Git-commit: 5dfdd24eb3d39d815bc952ae98128e967c9bba49
Patch-mainline: v4.19-rc4
References: bsc#1051510

Similarly to a recently reported bug in io_ti, a malicious USB device
could set port_number to a negative value and we would underflow the
port array in the interrupt completion handler.

As these devices only have one or two ports, fix this by making sure we
only consider the seventh bit when determining the port number (and
ignore bits 0xb0 which are typically set to 0x30).

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/usb/serial/ti_usb_3410_5052.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index 3010878f7f8e..e3c5832337e0 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -1119,7 +1119,7 @@ static void ti_break(struct tty_struct *tty, int break_state)
 
 static int ti_get_port_from_code(unsigned char code)
 {
-	return (code >> 4) - 3;
+	return (code >> 6) & 0x01;
 }
 
 static int ti_get_func_from_code(unsigned char code)
-- 
2.18.0