Change in coreboot[master]: libpayload: usbhid: Zero-initialize all parts of usbhid instance struct

[Julius Werner (Code Review)]

Hello Nico Huber, Patrick Georgi,

I'd like you to do a code review. Please visit

https://review.coreboot.org/23766

to review the following change.

Change subject: libpayload: usbhid: Zero-initialize all parts of usbhid instance struct
......................................................................

libpayload: usbhid: Zero-initialize all parts of usbhid instance struct

The USBHID driver zero-initializes some but not all of the fields in its
usbhid_inst_t structure. This is a problem because under some
circumstances, some of the uninitialized fields may be read and lead to
incorrect behavior. Some (broken) USB keyboards keep sending reports
that contain all zeroes even when they have no new keys... these usually
get silently ignored, but if the usbhid_inst_t structure is in an
inconsistent state where 'previous' is zeroed out but 'lastkeypress'
is non-zero because it wasn't properly initialized, these reports will
be interpreted as keyrepeats of the bogus 'lastkeypress'. This patch
changes the code to just xzalloc() the whole structure so we won't have
to worry about initialization issues anymore.

Change-Id: Ic987de2daaceaad2ae401a1e12b1bee397f802ee
Signed-off-by: Julius Werner 
---
M payloads/libpayload/drivers/usb/usbhid.c
1 file changed, 1 insertion(+), 5 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/66/23766/1

diff --git a/payloads/libpayload/drivers/usb/usbhid.c b/payloads/libpayload/drivers/usb/usbhid.c
index 3100d37..68130f8 100644
--- a/payloads/libpayload/drivers/usb/usbhid.c
+++ b/payloads/libpayload/drivers/usb/usbhid.c
@@ -439,11 +439,7 @@
    		boot_protos[interface->bInterfaceProtocol]);
    	switch (interface->bInterfaceProtocol) {
    	case hid_boot_proto_keyboard:
-			dev->data = malloc (sizeof (usbhid_inst_t));
-			if (!dev->data)
-				fatal("Not enough memory for USB HID device.\n");
-			memset(&HID_INST(dev)->previous, 0x00,
-			       sizeof(HID_INST(dev)->previous));
+			dev->data = xzalloc (sizeof (usbhid_inst_t));
    		usb_debug ("  configuring...\n");
    		usb_hid_set_protocol(dev, interface, hid_proto_boot);
    		usb_hid_set_idle(dev, interface, KEYBOARD_REPEAT_MS);