Re: [PATCH] net/usb: kalmia: Don't pass act_len in usb_bulk_msg error path

Alexander H Duyck
2023-02-10T16:08:53Z

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]
>
> With this in mind, let's just not pass act_len to the usb_bulk_msg error
> paths.
>
> 1: https://lore.kernel.org/lkml/Y9pY61y1nwTuzMOa@nanopsycho/
>
> 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>
> ---
> drivers/net/usb/kalmia.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> 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);

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>