Message-ID: <23e899f83c4f05a18deb2f86047d57d941205374.camel@gmail.com>
Subject: Re: [PATCH v2] net/usb: kalmia: Fix uninit-value in
 kalmia_send_init_packet
From:   Miko Larsson <mikoxyzzz@gmail.com>
To:     Jiri Pirko <jiri@resnulli.us>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-usb@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Greg KH <gregkh@linuxfoundation.org>
Date:   Thu, 09 Feb 2023 15:47:12 +0100
In-Reply-To: <Y9pY61y1nwTuzMOa@nanopsycho>
References: <7266fe67c835f90e5c257129014a63e79e849ef9.camel@gmail.com>
         <f0b62f38c042d2dcb8b8e83c827d76db2ac5d7ad.camel@gmail.com>
         <Y9pY61y1nwTuzMOa@nanopsycho>
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On Wed, 2023-02-01 at 13:19 +0100, Jiri Pirko wrote:
> Tue, Jan 31, 2023 at 03:20:33PM CET, mikoxyzzz@gmail.com=C2=A0wrote:
> > syzbot reports that act_len in kalmia_send_init_packet() is
> > uninitialized. Fix this by initializing it to 0.
> >=20
> > Fixes: d40261236e8e ("net/usb: Add Samsung Kalmia driver for
> > Samsung GT-B3730")
> > Reported-and-tested-by:
> > syzbot+cd80c5ef5121bfe85b55@syzkaller.appspotmail.com
> > Signed-off-by: Miko Larsson <mikoxyzzz@gmail.com>
> > ---
> > v1 -> v2
> > * Minor alteration of commit message.
> > * Added 'reported-and-tested-by' which is attributed to syzbot.
> >=20
> > drivers/net/usb/kalmia.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >=20
> > diff --git a/drivers/net/usb/kalmia.c b/drivers/net/usb/kalmia.c
> > index 9f2b70ef39aa..b158fb7bf66a 100644
> > --- a/drivers/net/usb/kalmia.c
> > +++ b/drivers/net/usb/kalmia.c
> > @@ -56,7 +56,7 @@ static int
> > kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8
> > init_msg_len,
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0u8 *buffer, u8 expected=
_len)
> > {
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0int act_len;
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0int act_len =3D 0;
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0int status;
> >=20
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0netdev_dbg(dev->net, "S=
ending init packet");
>=20
> Hmm, this is not the right fix.
>=20
> If the second call of usb_bulk_msg() in this function returns !=3D 0,
> the
> act_len printed out contains the value from previous usb_bulk_msg()
> call,
> which does not make sense.
>=20
> Printing act_len on error path is pointless, so rather remove it from
> the error message entirely for both usb_bulk_msg() calls.

Something like this, then?

diff --git a/drivers/net/usb/kalmia.c b/drivers/net/usb/kalmia.c
index 9f2b70ef39aa..613fc6910f14 100644
--- a/drivers/net/usb/kalmia.c
+++ b/drivers/net/usb/kalmia.c
@@ -65,8 +65,8 @@ kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg,=
 u8 init_msg_len,
 		init_msg, init_msg_len, &act_len, KALMIA_USB_TIMEOUT);
 	if (status !=3D 0) {
 		netdev_err(dev->net,
-			"Error sending init packet. Status %i, length %i\n",
-			status, act_len);
+			"Error sending init packet. Status %i\n",
+			status);
 		return status;
 	}
 	else if (act_len !=3D init_msg_len) {
@@ -83,8 +83,8 @@ kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg,=
 u8 init_msg_len,
=20
 	if (status !=3D 0)
 		netdev_err(dev->net,
-			"Error receiving init result. Status %i, length %i\n",
-			status, act_len);
+			"Error receiving init result. Status %i\n",
+			status);
 	else if (act_len !=3D expected_len)
 		netdev_err(dev->net, "Unexpected init result length: %i\n",
 			act_len);

--=20
~miko