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Message-Id: <20250526183607.66527-1-qasdev00@gmail.com>
Date: Mon, 26 May 2025 19:36:07 +0100
From: Qasim Ijaz <qasdev00@...il.com>
To: andrew+netdev@...n.ch,
davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com
Cc: linux-usb@...r.kernel.org,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
syzbot <syzbot+3361c2d6f78a3e0892f9@...kaller.appspotmail.com>,
stable@...r.kernel.org
Subject: [PATCH] net: ch9200: fix uninitialised access during mii_nway_restart
In mii_nway_restart() the code attempts to call
mii->mdio_read which is ch9200_mdio_read(). ch9200_mdio_read()
utilises a local buffer called "buff", which is initialised
with control_read(). However "buff" is conditionally
initialised inside control_read():
if (err == size) {
memcpy(data, buf, size);
}
If the condition of "err == size" is not met, then
"buff" remains uninitialised. Once this happens the
uninitialised "buff" is accessed and returned during
ch9200_mdio_read():
return (buff[0] | buff[1] << 8);
The problem stems from the fact that ch9200_mdio_read()
ignores the return value of control_read(), leading to
uinit-access of "buff".
To fix this we should check the return value of
control_read() and return early on error.
Reported-by: syzbot <syzbot+3361c2d6f78a3e0892f9@...kaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=3361c2d6f78a3e0892f9
Tested-by: syzbot <syzbot+3361c2d6f78a3e0892f9@...kaller.appspotmail.com>
Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices")
Cc: stable@...r.kernel.org
Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
---
drivers/net/usb/ch9200.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/net/usb/ch9200.c b/drivers/net/usb/ch9200.c
index f69d9b902da0..a206ffa76f1b 100644
--- a/drivers/net/usb/ch9200.c
+++ b/drivers/net/usb/ch9200.c
@@ -178,6 +178,7 @@ static int ch9200_mdio_read(struct net_device *netdev, int phy_id, int loc)
{
struct usbnet *dev = netdev_priv(netdev);
unsigned char buff[2];
+ int ret;
netdev_dbg(netdev, "%s phy_id:%02x loc:%02x\n",
__func__, phy_id, loc);
@@ -185,8 +186,10 @@ static int ch9200_mdio_read(struct net_device *netdev, int phy_id, int loc)
if (phy_id != 0)
return -ENODEV;
- control_read(dev, REQUEST_READ, 0, loc * 2, buff, 0x02,
- CONTROL_TIMEOUT_MS);
+ ret = control_read(dev, REQUEST_READ, 0, loc * 2, buff, 0x02,
+ CONTROL_TIMEOUT_MS);
+ if (ret < 0)
+ return ret;
return (buff[0] | buff[1] << 8);
}
--
2.39.5
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