Messages in this thread Patch in this message | | | Date | Mon, 16 Jul 2012 09:44:57 +0200 | Subject | Fwd: video/fbmem.c: Fix __u32 >= 0 condition in fb_do_show_logo. | From | Geert Uytterhoeven <> |
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Never reached lkml due to the HTML. Resending, with a CC to linux-fbdev added.
---------- Forwarded message ---------- From: Levin Du <zslevin@gmail.com> Date: 2012/7/12 Subject: video/fbmem.c: Fix __u32 >= 0 condition in fb_do_show_logo. To: linux-kernel@vger.kernel.org Cc: brad@neruo.com
Dear all,
Since dx or dy in struct fb_image is unsigned 32 bit integer:
struct fb_image { __u32 dx; /* Where to place image */ __u32 dy; ... }
In fb_do_show_logo(), image->dx or image->dy will always meet the >= 0 condition. if the logo is large enough (same as to the whole screen, for example) and rotate is UD or CCW, and image->dx or image->dy will results in a large value which makes info->fbops->fb_imageblit fail miserably.
Here is the raw patch:
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index ad93629..34a0ba3 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -419,6 +419,7 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image, int rotate, unsigned int num) { unsigned int x; + long d;
if (rotate == FB_ROTATE_UR) { for (x = 0; @@ -428,9 +429,10 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image, image->dx += image->width + 8; } } else if (rotate == FB_ROTATE_UD) { - for (x = 0; x < num && image->dx >= 0; x++) { + d = image->dx; + for (x = 0; x < num && d >= 0; x++) { info->fbops->fb_imageblit(info, image); - image->dx -= image->width + 8; + d -= image->width + 8; } } else if (rotate == FB_ROTATE_CW) { for (x = 0; @@ -440,9 +442,10 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image, image->dy += image->height + 8; } } else if (rotate == FB_ROTATE_CCW) { - for (x = 0; x < num && image->dy >= 0; x++) { + d = image->dy; + for (x = 0; x < num && d >= 0; x++) { info->fbops->fb_imageblit(info, image); - image->dy -= image->height + 8; + d -= image->height + 8; } } }
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
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