From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Tue, 28 Apr 2015 17:30:47 +0000 (+0200)
Subject: usb: chipidea: debug: avoid out of bound read
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=bd5fb0aec3dd7cde7ec4c397b10e55d4c9626d8d;p=linux-beck.git

usb: chipidea: debug: avoid out of bound read

A string written by the user may not be zero terminated.

sscanf may read memory beyond the buffer if no zero byte
is found.

For testing build with CONFIG_USB_CHIPIDEA=y, CONFIG_USB_CHIPIDEA_DEBUG=y.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
---

diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c
index dfb05edcdb96..5b7061a33103 100644
--- a/drivers/usb/chipidea/debug.c
+++ b/drivers/usb/chipidea/debug.c
@@ -88,9 +88,13 @@ static ssize_t ci_port_test_write(struct file *file, const char __user *ubuf,
 	char buf[32];
 	int ret;
 
-	if (copy_from_user(buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+	count = min_t(size_t, sizeof(buf) - 1, count);
+	if (copy_from_user(buf, ubuf, count))
 		return -EFAULT;
 
+	/* sscanf requires a zero terminated string */
+	buf[count] = '\0';
+
 	if (sscanf(buf, "%u", &mode) != 1)
 		return -EINVAL;