Message-ID: <9dc8b8dbfaf021af262ba349b8b92dab7962d8c4.camel@gmail.com>
Subject: Re: [PATCH] net/usb: kalmia: Don't pass act_len in usb_bulk_msg
 error path
From:   Alexander H Duyck <alexander.duyck@gmail.com>
To:     Miko Larsson <mikoxyzzz@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Cc:     Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Jiri Pirko <jiri@resnulli.us>, 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:   Fri, 10 Feb 2023 08:08:45 -0800
In-Reply-To: <2f74aab82a40e4c11c91ccba40f5b620f6cb209c.camel@gmail.com>
References: <7266fe67c835f90e5c257129014a63e79e849ef9.camel@gmail.com>
         <f0b62f38c042d2dcb8b8e83c827d76db2ac5d7ad.camel@gmail.com>
         <2f74aab82a40e4c11c91ccba40f5b620f6cb209c.camel@gmail.com>
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Precedence: bulk

On Fri, 2023-02-10 at 09:13 +0100, Miko Larsson wrote:
> syzbot reported that act_len in kalmia_send_init_packet() is
> uninitialized when passing it to the first usb_bulk_msg error path. Jiri
> Pirko noted that it's pointless to pass it in the error path, and that
> the value that would be printed in the second error path would be the
> value of act_len from the first call to usb_bulk_msg.[1]
>=20
> With this in mind, let's just not pass act_len to the usb_bulk_msg error
> paths.
>=20
> 1: https://lore.kernel.org/lkml/Y9pY61y1nwTuzMOa@nanopsycho/
>=20
> Fixes: d40261236e8e ("net/usb: Add Samsung Kalmia driver for Samsung GT-B=
3730")
> Reported-and-tested-by: syzbot+cd80c5ef5121bfe85b55@syzkaller.appspotmail=
.com
> Signed-off-by: Miko Larsson <mikoxyzzz@gmail.com>
> ---
>  drivers/net/usb/kalmia.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>=20
> 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_ms=
g, 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_ms=
g, 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);

Makes sense to me since the only possible return values for act_len
appear to be either uninitialized or 0 depending on where it fails.

Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>