| Message ID | 20250412183829.41342-2-qasdev00@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | net: ch9200: fix various bugs and improve qinheng ch9200 driver | expand |
On Sat, Apr 12, 2025 at 07:38:25PM +0100, Qasim Ijaz wrote: > In mii_nway_restart() during the line: > > bmcr = mii->mdio_read(mii->dev, mii->phy_id, MII_BMCR); > > The code attempts to call mii->mdio_read which is ch9200_mdio_read(). > > ch9200_mdio_read() utilises a local buffer, which is initialised > with control_read(): > > unsigned char buff[2]; > > 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. We return 0 on control_read() failure here > because returning a negative may trigger the "bmcr & BMCR_ANENABLE" > check within mii_nway_restart. > > Reported-by: syzbot <syzbot+3361c2d6f78a3e0892f9@syzkaller.appspotmail.com> > Closes: https://syzkaller.appspot.com/bug?extid=3361c2d6f78a3e0892f9 > Tested-by: syzbot <syzbot+3361c2d6f78a3e0892f9@syzkaller.appspotmail.com> > Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices") > Cc: stable@vger.kernel.org > Signed-off-by: Qasim Ijaz <qasdev00@gmail.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Andrew
diff --git a/drivers/net/usb/ch9200.c b/drivers/net/usb/ch9200.c index f69d9b902da0..4f29ecf2240a 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 0; return (buff[0] | buff[1] << 8); }
In mii_nway_restart() during the line: bmcr = mii->mdio_read(mii->dev, mii->phy_id, MII_BMCR); The code attempts to call mii->mdio_read which is ch9200_mdio_read(). ch9200_mdio_read() utilises a local buffer, which is initialised with control_read(): unsigned char buff[2]; 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. We return 0 on control_read() failure here because returning a negative may trigger the "bmcr & BMCR_ANENABLE" check within mii_nway_restart. Reported-by: syzbot <syzbot+3361c2d6f78a3e0892f9@syzkaller.appspotmail.com> Closes: https://syzkaller.appspot.com/bug?extid=3361c2d6f78a3e0892f9 Tested-by: syzbot <syzbot+3361c2d6f78a3e0892f9@syzkaller.appspotmail.com> Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices") Cc: stable@vger.kernel.org Signed-off-by: Qasim Ijaz <qasdev00@gmail.com> --- drivers/net/usb/ch9200.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)