[PATCH v2 01/14] drm/fb-helper: keep the .gamma_store updated in drm_fb_helper_setcmap

[Peter Rosin]

I think the gamma_store can end up invalid on error. But the way I read
it, that can happen in drm_mode_gamma_set_ioctl as well, so why should
this pesky legacy fbdev stuff be any better?

Signed-off-by: Peter Rosin <p...@axentia.se>
---
 drivers/gpu/drm/drm_fb_helper.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

This is an alternative version rebased on top of Daniels "fbdev helper
locking rework and deferred setup" series.

Cheers,
peda

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index a4cfef9..c7122c9 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1330,12 +1330,16 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct 
fb_info *info)
        const struct drm_crtc_helper_funcs *crtc_funcs;
        u16 *red, *green, *blue, *transp;
        struct drm_crtc *crtc;
+       u16 *r, *g, *b;
        int i, j, rc = 0;
        int start;
 
        if (oops_in_progress)
                return -EBUSY;
 
+       if (cmap->start + cmap->len < cmap->start)
+               return -EINVAL;
+
        mutex_lock(&fb_helper->lock);
        if (!drm_fb_helper_is_bound(fb_helper)) {
                mutex_unlock(&fb_helper->lock);
@@ -1353,6 +1357,29 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct 
fb_info *info)
                transp = cmap->transp;
                start = cmap->start;
 
+               if (info->fix.visual != FB_VISUAL_TRUECOLOR) {
+                       if (!crtc->gamma_size) {
+                               rc = -EINVAL;
+                               goto out;
+                       }
+
+                       if (cmap->start + cmap->len > crtc->gamma_size) {
+                               rc = -EINVAL;
+                               goto out;
+                       }
+
+                       r = crtc->gamma_store;
+                       g = r + crtc->gamma_size;
+                       b = g + crtc->gamma_size;
+
+                       memcpy(r + cmap->start, cmap->red,
+                              cmap->len * sizeof(u16));
+                       memcpy(g + cmap->start, cmap->green,
+                              cmap->len * sizeof(u16));
+                       memcpy(b + cmap->start, cmap->blue,
+                              cmap->len * sizeof(u16));
+               }
+
                for (j = 0; j < cmap->len; j++) {
                        u16 hred, hgreen, hblue, htransp = 0xffff;
 
-- 
2.1.4