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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Himadri Pandya <himadrispandya@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.9 62/71] net: usb: Fix uninit-was-stored issue in asix_read_phy_addr()
Date:   Fri, 11 Sep 2020 14:46:46 +0200
Message-Id: <20200911122508.003816840@linuxfoundation.org>
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From: Himadri Pandya <himadrispandya@gmail.com>

commit a092b7233f0e000cc6f2c71a49e2ecc6f917a5fc upstream.

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/usb/asix_common.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -277,7 +277,7 @@ int asix_read_phy_addr(struct usbnet *de
 
 	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;
 	}