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From:   Himadri Pandya <himadrispandya@gmail.com>
To:     davem@davemloft.net, kuba@kernel.org
Cc:     linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        linux-kernel-mentees@lists.linuxfoundation.org,
        gregkh@linuxfoundation.org,
        Himadri Pandya <himadrispandya@gmail.com>
Subject: [PATCH] net: usb: Fix uninit-was-stored issue in asix_read_phy_addr()
Date:   Thu, 27 Aug 2020 12:23:55 +0530
Message-Id: <20200827065355.15177-1-himadrispandya@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The buffer size is 2 Bytes and we expect to receive the same amount of
data. But sometimes we receive less data and run into uninit-was-stored
issue upon read. Hence modify the error check on the return value to match
with the buffer size as a prevention.

Reported-and-tested by: syzbot+a7e220df5a81d1ab400e@syzkaller.appspotmail.com
Signed-off-by: Himadri Pandya <himadrispandya@gmail.com>
---
 drivers/net/usb/asix_common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index e39f41efda3e..7bc6e8f856fe 100644
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -296,7 +296,7 @@ int asix_read_phy_addr(struct usbnet *dev, int internal)
 
 	netdev_dbg(dev->net, "asix_get_phy_addr()\n");
 
-	if (ret < 0) {
+	if (ret < 2) {
 		netdev_err(dev->net, "Error reading PHYID register: %02x\n", ret);
 		goto out;
 	}
-- 
2.17.1