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drm/fb-helper: Fix height, width, and accel_flags in fb_var

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Fbtest contains some very simple validation of the fbdev userspace API
contract.  When used with shmob-drm, it reports the following warnings
and errors:

    height changed from 68 to 0
    height was rounded down
    width changed from 111 to 0
    width was rounded down
    accel_flags changed from 0 to 1

The first part happens because __fill_var() resets the physical
dimensions of the first connector, as filled in by drm_setup_crtcs_fb().
Fix this by retaining the original values.

The last part happens because __fill_var() forces the FB_ACCELF_TEXT
flag on, while fbtest disables all acceleration on purpose, so it can
draw safely to the frame buffer.  Fix this by setting accel_flags to
zero, as DRM does not implement any text console acceleration.
Note that this issue can also be seen in the output of fbset, which
reports "accel true".

Fixes: ee4cce0a8f03a333 ("drm/fb-helper: fix input validation gaps in check_var")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/57e6b334dae8148b1b8ae6ef308ce9a83810a850.1684854344.git.geert+renesas@glider.be
This commit is contained in:
Geert Uytterhoeven 2023-05-23 17:06:20 +02:00 committed by Thomas Zimmermann
parent e997c218ad
commit e79d85c6c2
1 changed files with 7 additions and 5 deletions

12
drivers/gpu/drm/drm_fb_helper.c

@ -1545,17 +1545,19 @@ static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
}
}
static void __fill_var(struct fb_var_screeninfo *var,
static void __fill_var(struct fb_var_screeninfo *var, struct fb_info *info,
struct drm_framebuffer *fb)
{
int i;
var->xres_virtual = fb->width;
var->yres_virtual = fb->height;
var->accel_flags = FB_ACCELF_TEXT;
var->accel_flags = 0;
var->bits_per_pixel = drm_format_info_bpp(fb->format, 0);
var->height = var->width = 0;
var->height = info->var.height;
var->width = info->var.width;
var->left_margin = var->right_margin = 0;
var->upper_margin = var->lower_margin = 0;
var->hsync_len = var->vsync_len = 0;
@ -1618,7 +1620,7 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
return -EINVAL;
}
__fill_var(var, fb);
__fill_var(var, info, fb);
/*
* fb_pan_display() validates this, but fb_set_par() doesn't and just
@ -2074,7 +2076,7 @@ static void drm_fb_helper_fill_var(struct fb_info *info,
info->pseudo_palette = fb_helper->pseudo_palette;
info->var.xoffset = 0;
info->var.yoffset = 0;
__fill_var(&info->var, fb);
__fill_var(&info->var, info, fb);
info->var.activate = FB_ACTIVATE_NOW;
drm_fb_helper_fill_pixel_fmt(&info->var, format);