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    Subject[PATCH 4.14 36/69] media: smsusb: better handle optional alignment
    Date
    From: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

    commit a47686636d84eaec5c9c6e84bd5f96bed34d526d upstream.

    Most Siano devices require an alignment for the response.

    Changeset f3be52b0056a ("media: usb: siano: Fix general protection fault in smsusb")
    changed the logic with gets such aligment, but it now produces a
    sparce warning:

    drivers/media/usb/siano/smsusb.c: In function 'smsusb_init_device':
    drivers/media/usb/siano/smsusb.c:447:37: warning: 'in_maxp' may be used uninitialized in this function [-Wmaybe-uninitialized]
    447 | dev->response_alignment = in_maxp - sizeof(struct sms_msg_hdr);
    | ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

    The sparse message itself is bogus, but a broken (or fake) USB
    eeprom could produce a negative value for response_alignment.

    So, change the code in order to check if the result is not
    negative.

    Fixes: 31e0456de5be ("media: usb: siano: Fix general protection fault in smsusb")
    CC: <stable@vger.kernel.org>
    Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/media/usb/siano/smsusb.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    --- a/drivers/media/usb/siano/smsusb.c
    +++ b/drivers/media/usb/siano/smsusb.c
    @@ -402,7 +402,7 @@ static int smsusb_init_device(struct usb
    struct smsusb_device_t *dev;
    void *mdev;
    int i, rc;
    - int in_maxp = 0;
    + int align = 0;

    /* create device object */
    dev = kzalloc(sizeof(struct smsusb_device_t), GFP_KERNEL);
    @@ -420,14 +420,14 @@ static int smsusb_init_device(struct usb

    if (desc->bEndpointAddress & USB_DIR_IN) {
    dev->in_ep = desc->bEndpointAddress;
    - in_maxp = usb_endpoint_maxp(desc);
    + align = usb_endpoint_maxp(desc) - sizeof(struct sms_msg_hdr);
    } else {
    dev->out_ep = desc->bEndpointAddress;
    }
    }

    pr_debug("in_ep = %02x, out_ep = %02x\n", dev->in_ep, dev->out_ep);
    - if (!dev->in_ep || !dev->out_ep) { /* Missing endpoints? */
    + if (!dev->in_ep || !dev->out_ep || align < 0) { /* Missing endpoints? */
    smsusb_term_device(intf);
    return -ENODEV;
    }
    @@ -446,7 +446,7 @@ static int smsusb_init_device(struct usb
    /* fall-thru */
    default:
    dev->buffer_size = USB2_BUFFER_SIZE;
    - dev->response_alignment = in_maxp - sizeof(struct sms_msg_hdr);
    + dev->response_alignment = align;

    params.flags |= SMS_DEVICE_FAMILY2;
    break;

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