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drm/fb-helper: fix input validation gaps in check_var 

Apparently drivers need to check all this stuff themselves, which for
most things makes sense I guess. And for everything else we luck out,
because modern distros stopped supporting any other fbdev drivers than
drm ones and I really don't want to argue anymore about who needs to
check stuff. Therefore fixing all this just for drm fbdev emulation is
good enough.

Note that var->active is not set or validated. This is just control
flow for fbmem.c and needs to be validated in there as needed.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230404194038.472803-3-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2023-04-04 21:40:38 +02:00
parent 36e239b5d5
commit ee4cce0a8f
1 changed files with 38 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
drivers/gpu/drm/drm_fb_helper.c
View File

@ -1537,6 +1537,27 @@ static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
}
}
static void __fill_var(struct fb_var_screeninfo *var,
struct drm_framebuffer *fb)
{
int i;
var->xres_virtual = fb->width;
var->yres_virtual = fb->height;
var->accel_flags = FB_ACCELF_TEXT;
var->bits_per_pixel = drm_format_info_bpp(fb->format, 0);
var->height = var->width = 0;
var->left_margin = var->right_margin = 0;
var->upper_margin = var->lower_margin = 0;
var->hsync_len = var->vsync_len = 0;
var->sync = var->vmode = 0;
var->rotate = 0;
var->colorspace = 0;
for (i = 0; i < 4; i++)
var->reserved[i] = 0;
}
/**
* drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
* @var: screeninfo to check
@ -1589,8 +1610,22 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
return -EINVAL;
}
var->xres_virtual = fb->width;
var->yres_virtual = fb->height;
__fill_var(var, fb);
/*
* fb_pan_display() validates this, but fb_set_par() doesn't and just
* falls over. Note that __fill_var above adjusts y/res_virtual.
*/
if (var->yoffset > var->yres_virtual - var->yres ||
var->xoffset > var->xres_virtual - var->xres)
return -EINVAL;
/* We neither support grayscale nor FOURCC (also stored in here). */
if (var->grayscale > 0)
return -EINVAL;
if (var->nonstd)
return -EINVAL;
/*
* Workaround for SDL 1.2, which is known to be setting all pixel format
@ -1606,11 +1641,6 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
drm_fb_helper_fill_pixel_fmt(var, format);
}
/*
* Likewise, bits_per_pixel should be rounded up to a supported value.
*/
var->bits_per_pixel = bpp;
/*
* drm fbdev emulation doesn't support changing the pixel format at all,
* so reject all pixel format changing requests.
@ -2034,12 +2064,9 @@ static void drm_fb_helper_fill_var(struct fb_info *info,
}
info->pseudo_palette = fb_helper->pseudo_palette;
info->var.xres_virtual = fb->width;
info->var.yres_virtual = fb->height;
info->var.bits_per_pixel = drm_format_info_bpp(format, 0);
info->var.accel_flags = FB_ACCELF_TEXT;
info->var.xoffset = 0;
info->var.yoffset = 0;
__fill_var(&info->var, fb);
info->var.activate = FB_ACTIVATE_NOW;
drm_fb_helper_fill_pixel_fmt(&info->var, format);