gspca_sn9c20x: Fix NULL pointer dereference

Don't call v4l2_ctrl_g_ctrl on ctrls which the model cam in question
does not have.

Reported-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
[ Taken directly, since Mauro is on vacation ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/media/video/gspca/sn9c20x.c b/drivers/media/video/gspca/sn9c20x.c
index 6c31e46a1fd2ed4356b829abf916fee6e215b63e..b9c6f17eabb245fde118e3b198f163782d92a7bc 100644 (file)
--- a/drivers/media/video/gspca/sn9c20x.c
+++ b/drivers/media/video/gspca/sn9c20x.c
@@ -2070,10 +2070,13 @@ static int sd_start(struct gspca_dev *gspca_dev)
        set_gamma(gspca_dev, v4l2_ctrl_g_ctrl(sd->gamma));
        set_redblue(gspca_dev, v4l2_ctrl_g_ctrl(sd->blue),
                        v4l2_ctrl_g_ctrl(sd->red));
-       set_gain(gspca_dev, v4l2_ctrl_g_ctrl(sd->gain));
-       set_exposure(gspca_dev, v4l2_ctrl_g_ctrl(sd->exposure));
-       set_hvflip(gspca_dev, v4l2_ctrl_g_ctrl(sd->hflip),
-                       v4l2_ctrl_g_ctrl(sd->vflip));
+       if (sd->gain)
+               set_gain(gspca_dev, v4l2_ctrl_g_ctrl(sd->gain));
+       if (sd->exposure)
+               set_exposure(gspca_dev, v4l2_ctrl_g_ctrl(sd->exposure));
+       if (sd->hflip)
+               set_hvflip(gspca_dev, v4l2_ctrl_g_ctrl(sd->hflip),
+                               v4l2_ctrl_g_ctrl(sd->vflip));
 
        reg_w1(gspca_dev, 0x1007, 0x20);
        reg_w1(gspca_dev, 0x1061, 0x03);
@@ -2176,7 +2179,7 @@ static void sd_dqcallback(struct gspca_dev *gspca_dev)
        struct sd *sd = (struct sd *) gspca_dev;
        int avg_lum;
 
-       if (!v4l2_ctrl_g_ctrl(sd->autogain))
+       if (sd->autogain == NULL || !v4l2_ctrl_g_ctrl(sd->autogain))
                return;
 
        avg_lum = atomic_read(&sd->avg_lum);