[PATCH] rt2x00: reset reg earlier in rt2500usb_register_read

From: Dongliang Mu
Date: Thu Jan 21 2021 - 04:22:31 EST

In the function rt2500usb_register_read(_lock), reg is uninitialized
in some situation. Then KMSAN reports uninit-value at its first memory
access. To fix this issue, add one reg initialization in the function
rt2500usb_register_read and rt2500usb_register_read_lock

BUG: KMSAN: uninit-value in rt2500usb_init_eeprom rt2500usb.c:1443 [inline]
BUG: KMSAN: uninit-value in rt2500usb_probe_hw+0xb5e/0x22a0 rt2500usb.c:1757
CPU: 0 PID: 3369 Comm: kworker/0:2 Not tainted 5.3.0-rc7+ #0
Hardware name: Google Compute Engine
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x191/0x1f0 lib/dump_stack.c:113
kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
__msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294
rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1443 [inline]
rt2500usb_probe_hw+0xb5e/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
rt2x00usb_probe+0x7ae/0xf60 wireless/ralink/rt2x00/rt2x00usb.c:842
rt2500usb_probe+0x50/0x60 wireless/ralink/rt2x00/rt2500usb.c:1966
......

Local variable description: ----reg.i.i@rt2500usb_probe_hw
Variable was created at:
rt2500usb_register_read wireless/ralink/rt2x00/rt2500usb.c:51 [inline]
rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1440 [inline]
rt2500usb_probe_hw+0x774/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427

Signed-off-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx>
---
drivers/net/wireless/ralink/rt2x00/rt2500usb.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
index fce05fc88aaf..f6c93a25b18c 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
@@ -48,6 +48,7 @@ static u16 rt2500usb_register_read(struct rt2x00_dev *rt2x00dev,
const unsigned int offset)
{
__le16 reg;
+ memset(&reg, 0, sizeof(reg));
rt2x00usb_vendor_request_buff(rt2x00dev, USB_MULTI_READ,
USB_VENDOR_REQUEST_IN, offset,
&reg, sizeof(reg));
@@ -58,6 +59,7 @@ static u16 rt2500usb_register_read_lock(struct rt2x00_dev *rt2x00dev,
const unsigned int offset)
{
__le16 reg;
+ memset(&reg, 0, sizeof(reg));
rt2x00usb_vendor_req_buff_lock(rt2x00dev, USB_MULTI_READ,
USB_VENDOR_REQUEST_IN, offset,
&reg, sizeof(reg), REGISTER_TIMEOUT);
--
2.25.1