Re: [PATCH] fbdev: colormap fixes

[Jon Smirl <jonsmirl@gmail.com>]

Can you review this fix for the issues below? I fixed things to
automatically adjust the number of entries to whatever fits in
PAGE_SIZE.

diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c
--- a/drivers/video/fbsysfs.c
+++ b/drivers/video/fbsysfs.c
@@ -244,15 +244,15 @@ static ssize_t show_virtual(struct class
 
 /* Format for cmap is "%02x%c%4x%4x%4x\n" */
 /* %02x entry %c transp %4x red %4x blue %4x green \n */
-/* 255 rows at 16 chars equals 4096 */
-/* PAGE_SIZE can be 4096 or larger */
+/* 256 rows at 16 chars equals 4096, the normal page size */
+/* the code will automatically adjust for different page sizes */
 static ssize_t store_cmap(struct class_device *class_device, const char *buf,
 			  size_t count)
 {
 	struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
 	int rc, i, start, length, transp = 0;
 
-	if ((count > 4096) || ((count % 16) != 0) || (PAGE_SIZE < 4096))
+	if ((count > PAGE_SIZE) || ((count % 16) != 0))
 		return -EINVAL;
 
 	if (!fb_info->fbops->fb_setcolreg && !fb_info->fbops->fb_setcmap)
@@ -317,18 +317,18 @@ static ssize_t show_cmap(struct class_de
 	   !fb_info->cmap.green)
 		return -EINVAL;
 
-	if (PAGE_SIZE < 4096)
+	if (fb_info->cmap.len > PAGE_SIZE / 16)
 		return -EINVAL;
 
 	/* don't mess with the format, the buffer is PAGE_SIZE */
-	/* 255 entries at 16 chars per line equals 4096 = PAGE_SIZE */
+	/* 256 entries at 16 chars per line equals 4096 = PAGE_SIZE */
 	for (i = 0; i < fb_info->cmap.len; i++) {
-		sprintf(&buf[ i * 16], "%02x%c%4x%4x%4x\n", i + fb_info->cmap.start,
+		snprintf(&buf[ i * 16], PAGE_SIZE - i * 16, "%02x%c%4x%4x%4x\n", i
+ fb_info->cmap.start,
 			((fb_info->cmap.transp && fb_info->cmap.transp[i]) ? '*' : ' '),
 			fb_info->cmap.red[i], fb_info->cmap.blue[i],
 			fb_info->cmap.green[i]);
 	}
-	return 4096;
+	return 16 * fb_info->cmap.len;
 }
 
 static ssize_t store_blank(struct class_device *class_device, const char * buf,



On 7/28/05, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Wed, 27 Jul 2005, Linux Kernel Mailing List wrote:
> > tree 17014af0ea8b19dae7848736d324499715b7a1a3
> > parent 3ca34fcbfbf8a7cbe99d54ae81c4e28fdc6f4ac6
> > author Jon Smirl <jonsmirl@gmail.com> Thu, 28 Jul 2005 01:46:05 -0700
> > committer Linus Torvalds <torvalds@g5.osdl.org> Thu, 28 Jul 2005 06:26:18 -0700
> >
> > [PATCH] fbdev: colormap fixes
> >
> > Color maps have up to 256 entries.  4096/256 allows for 16 characters per
>              ^^^^^^^^^^^^^^^^^^^^^^
> Most (all?) current drivers have this limitation. But there exists hardware
> with more entries.
> 
> > line.  The format for a cmap entry is "%02x%c%4x%4x%4x\n" %02x entry %c
> > transp %4x red %4x blue %4x green
> >
> > You can read the color_map with cat fb0/color_map.
> >
> > Signed-off-by: Jon Smirl <jonsmirl@gmail.com>
> > Signed-off-by: Andrew Morton <akpm@osdl.org>
> > Signed-off-by: Linus Torvalds <torvalds@osdl.org>
> >
> >  drivers/video/fbsysfs.c |   82 ++++++++++++++++++++++++++++++++++++++++++------
> >  1 files changed, 72 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c
> > --- a/drivers/video/fbsysfs.c
> > +++ b/drivers/video/fbsysfs.c
> > @@ -242,10 +242,68 @@ static ssize_t show_virtual(struct class
> >                       fb_info->var.yres_virtual);
> >  }
> >
> > -static ssize_t store_cmap(struct class_device *class_device, const char * buf,
> > +/* Format for cmap is "%02x%c%4x%4x%4x\n" */
> > +/* %02x entry %c transp %4x red %4x blue %4x green \n */
> > +/* 255 rows at 16 chars equals 4096 */
>       ^^^
> 256?
> 
> > +/* PAGE_SIZE can be 4096 or larger */
> > +static ssize_t store_cmap(struct class_device *class_device, const char *buf,
> >                         size_t count)
> >  {
> > -//   struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
> > +     struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
> > +     int rc, i, start, length, transp = 0;
> > +
> > +     if ((count > 4096) || ((count % 16) != 0) || (PAGE_SIZE < 4096))
> > +             return -EINVAL;
> > +
> > +     if (!fb_info->fbops->fb_setcolreg && !fb_info->fbops->fb_setcmap)
> > +             return -EINVAL;
> > +
> > +     sscanf(buf, "%02x", &start);
> > +     length = count / 16;
> > +
> > +     for (i = 0; i < length; i++)
> > +             if (buf[i * 16 + 2] != ' ')
> > +                     transp = 1;
> > +
> > +     /* If we can batch, do it */
> > +     if (fb_info->fbops->fb_setcmap && length > 1) {
> > +             struct fb_cmap umap;
> > +
> > +             memset(&umap, 0, sizeof(umap));
> > +             if ((rc = fb_alloc_cmap(&umap, length, transp)))
> > +                     return rc;
> > +
> > +             umap.start = start;
> > +             for (i = 0; i < length; i++) {
> > +                     sscanf(&buf[i * 16 +  3], "%4hx", &umap.red[i]);
> > +                     sscanf(&buf[i * 16 +  7], "%4hx", &umap.blue[i]);
> > +                     sscanf(&buf[i * 16 + 11], "%4hx", &umap.green[i]);
> > +                     if (transp)
> > +                             umap.transp[i] = (buf[i * 16 +  2] != ' ');
> > +             }
> > +             rc = fb_info->fbops->fb_setcmap(&umap, fb_info);
> > +             fb_copy_cmap(&umap, &fb_info->cmap);
> > +             fb_dealloc_cmap(&umap);
> > +
> > +             return rc;
> > +     }
> > +     for (i = 0; i < length; i++) {
> > +             u16 red, blue, green, tsp;
> > +
> > +             sscanf(&buf[i * 16 +  3], "%4hx", &red);
> > +             sscanf(&buf[i * 16 +  7], "%4hx", &blue);
> > +             sscanf(&buf[i * 16 + 11], "%4hx", &green);
> > +             tsp = (buf[i * 16 +  2] != ' ');
> > +             if ((rc = fb_info->fbops->fb_setcolreg(start++,
> > +                                   red, green, blue, tsp, fb_info)))
> > +                     return rc;
> > +
> > +             fb_info->cmap.red[i] = red;
> > +             fb_info->cmap.blue[i] = blue;
> > +             fb_info->cmap.green[i] = green;
> > +             if (transp)
> > +                     fb_info->cmap.transp[i] = tsp;
> > +     }
> >       return 0;
> >  }
> >
> > @@ -253,20 +311,24 @@ static ssize_t show_cmap(struct class_de
> >  {
> >       struct fb_info *fb_info =
> >               (struct fb_info *)class_get_devdata(class_device);
> > -     unsigned int offset = 0, i;
> > +     unsigned int i;
> >
> >       if (!fb_info->cmap.red || !fb_info->cmap.blue ||
> > -         !fb_info->cmap.green || !fb_info->cmap.transp)
> > +        !fb_info->cmap.green)
> > +             return -EINVAL;
> > +
> > +     if (PAGE_SIZE < 4096)
> >               return -EINVAL;
> >
> > +     /* don't mess with the format, the buffer is PAGE_SIZE */
> > +     /* 255 entries at 16 chars per line equals 4096 = PAGE_SIZE */
>            ^^^
> 256?
> 
> >       for (i = 0; i < fb_info->cmap.len; i++) {
> > -             offset += snprintf(buf, PAGE_SIZE - offset,
> > -                                "%d,%d,%d,%d,%d\n", i + fb_info->cmap.start,
> > -                                fb_info->cmap.red[i], fb_info->cmap.blue[i],
> > -                                fb_info->cmap.green[i],
> > -                                fb_info->cmap.transp[i]);
> > +             sprintf(&buf[ i * 16], "%02x%c%4x%4x%4x\n", i + fb_info->cmap.start,
> 
> Woops, nice buffer overflow if fb_info->cmap.len > 256...
> 
> > +                     ((fb_info->cmap.transp && fb_info->cmap.transp[i]) ? '*' : ' '),
> > +                     fb_info->cmap.red[i], fb_info->cmap.blue[i],
> > +                     fb_info->cmap.green[i]);
> >       }
> > -     return offset;
> > +     return 4096;
>                ^^^^
> 
> What if fb_info->cmap.len is smaller than 256?
> 
> >  }
> 
> Gr{oetje,eeting}s,
> 
>                                                 Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                                             -- Linus Torvalds
> 


-- 
Jon Smirl
jonsmirl@gmail.com