netdev - Re: [PATCH v2] net/usb: kalmia: Fix uninit-value in kalmia_send_init

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Message-ID: <23e899f83c4f05a18deb2f86047d57d941205374.camel@gmail.com>
Date:   Thu, 09 Feb 2023 15:47:12 +0100
From:   Miko Larsson <mikoxyzzz@...il.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-usb@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v2] net/usb: kalmia: Fix uninit-value in
 kalmia_send_init_packet

On Wed, 2023-02-01 at 13:19 +0100, Jiri Pirko wrote:
> Tue, Jan 31, 2023 at 03:20:33PM CET, mikoxyzzz@...il.com wrote:
> > syzbot reports that act_len in kalmia_send_init_packet() is
> > uninitialized. Fix this by initializing it to 0.
> > 
> > Fixes: d40261236e8e ("net/usb: Add Samsung Kalmia driver for
> > Samsung GT-B3730")
> > Reported-and-tested-by:
> > syzbot+cd80c5ef5121bfe85b55@...kaller.appspotmail.com
> > Signed-off-by: Miko Larsson <mikoxyzzz@...il.com>
> > ---
> > v1 -> v2
> > * Minor alteration of commit message.
> > * Added 'reported-and-tested-by' which is attributed to syzbot.
> > 
> > drivers/net/usb/kalmia.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > 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,
> >         u8 *buffer, u8 expected_len)
> > {
> > -       int act_len;
> > +       int act_len = 0;
> >         int status;
> > 
> >         netdev_dbg(dev->net, "Sending init packet");
> 
> Hmm, this is not the right fix.
> 
> If the second call of usb_bulk_msg() in this function returns != 0,
> the
> act_len printed out contains the value from previous usb_bulk_msg()
> call,
> which does not make sense.
> 
> 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 != 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 != init_msg_len) {
@@ -83,8 +83,8 @@ kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8 init_msg_len,
 
 	if (status != 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 != expected_len)
 		netdev_err(dev->net, "Unexpected init result length: %i\n",
 			act_len);

-- 
~miko