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 <[email protected]>
Reported-and-tested-by: [email protected]
---
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;
+ netdev_err(dev->net, "MDIO read error: %d\n", err);
+ return err;
+ }
netdev_dbg(dev->net,
"dm9601_mdio_read() phy_id=0x%02x, loc=0x%02x, returns=0x%04x\n",
---
base-commit: 94f6f0550c625fab1f373bb86a6669b45e9748b3
change-id: 20231009-topic-dm9601_uninit_mdio_read-a15918ffbd6f
Best regards,
--
Javier Carrasco <[email protected]>
>>>>> "Javier" == Javier Carrasco <[email protected]> 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 <[email protected]>
> Reported-and-tested-by: [email protected]
> ---
> 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 <[email protected]>
--
Bye, Peter Korsgaard
Hi Peter,
On 09.10.23 22:48, Peter Korsgaard wrote:
>
> > 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 <[email protected]>
> > Reported-and-tested-by: [email protected]
> > ---
> > 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.You are right, I just simulated the err = 0 value from
__usbnet_read_cmd() and in this case it is harmless because dm_read is
called with length != 0 (in dm_read_shared_word either 1 or 2) and
therefore it returns -EINVAL. A silly case where this would fail would
be if length == 0, which would be wrong anyways.
So I will remove the err == 0 case for v2.
Thanks a lot for your feedback.
> Acked-by: Peter Korsgaard <[email protected]>
>
Best regards,
Javier Carrasco