video: uvesafb: Fix integer overflow in allocation

CVE-2018-13406

cmap->len can get close to INT_MAX/2, allowing for an integer overflow in
allocation. This uses kmalloc_array() instead to catch the condition.

Reported-by: Dr Silvio Cesare of InfoSect <silvio.cesare@gmail.com>
Fixes: 8bdb3a2d7df48 ("uvesafb: the driver core")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
(cherry picked from commit 9f645bcc566a1e9f921bdae7528a01ced5bc3713)
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/video/fbdev/uvesafb.c b/drivers/video/fbdev/uvesafb.c
index 73676eb0244a7bd63d294619563d723992a93183..c592ca513115c060e37133c87411efad58bbc1ad 100644 (file)
--- a/drivers/video/fbdev/uvesafb.c
+++ b/drivers/video/fbdev/uvesafb.c
@@ -1044,7 +1044,8 @@ static int uvesafb_setcmap(struct fb_cmap *cmap, struct fb_info *info)
                    info->cmap.len || cmap->start < info->cmap.start)
                        return -EINVAL;
 
-               entries = kmalloc(sizeof(*entries) * cmap->len, GFP_KERNEL);
+               entries = kmalloc_array(cmap->len, sizeof(*entries),
+                                       GFP_KERNEL);
                if (!entries)
                        return -ENOMEM;