>>>>> "Javier" == Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx> writes: > syzbot has found an uninit-value bug triggered by the dm9601 driver [1]. > This error happens because the variable res is not updated if the call > to dm_read_shared_word returns an error or if no data is read (see > __usbnet_read_cmd()). In this particular case -EPROTO was returned and > res stayed uninitialized. > This can be avoided by checking the return value of dm_read_shared_word > and returning an error if the read operation failed or no data was read. > [1] https://syzkaller.appspot.com/bug?extid=1f53a30781af65d2c955 > Signed-off-by: Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx> > Reported-and-tested-by: syzbot+1f53a30781af65d2c955@xxxxxxxxxxxxxxxxxxxxxxxxx > --- > drivers/net/usb/dm9601.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > diff --git a/drivers/net/usb/dm9601.c b/drivers/net/usb/dm9601.c > index 48d7d278631e..e223daa93229 100644 > --- a/drivers/net/usb/dm9601.c > +++ b/drivers/net/usb/dm9601.c > @@ -222,13 +222,20 @@ static int dm9601_mdio_read(struct net_device *netdev, int phy_id, int loc) > struct usbnet *dev = netdev_priv(netdev); > __le16 res; > + int err; > if (phy_id) { > netdev_dbg(dev->net, "Only internal phy supported\n"); > return 0; > } > - dm_read_shared_word(dev, 1, loc, &res); > + err = dm_read_shared_word(dev, 1, loc, &res); > + if (err <= 0) { > + if (err == 0) > + err = -ENODATA; Looking at dm_read(), it doesn't look like we can end up here with err == 0, but OK. Acked-by: Peter Korsgaard <peter@xxxxxxxxxxxxx> -- Bye, Peter Korsgaard
