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 dfb05ed..5b7061a 100644
--- a/drivers/usb/chipidea/debug.c
+++ b/drivers/usb/chipidea/debug.c
@@ -88,9 +88,13 @@
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;