[CVE-2018-13406][X/A/B][SRU][PATCH] video: uvesafb: Fix integer overflow in allocation

[Po-Hsu Lin]

From: Kees Cook <keescook at chromium.org>

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 at gmail.com>
Fixes: 8bdb3a2d7df48 ("uvesafb: the driver core")
Cc: stable at vger.kernel.org
Signed-off-by: Kees Cook <keescook at chromium.org>
(cherry picked from commit 9f645bcc566a1e9f921bdae7528a01ced5bc3713)
Signed-off-by: Po-Hsu Lin <po-hsu.lin at canonical.com>
---
 drivers/video/fbdev/uvesafb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/uvesafb.c b/drivers/video/fbdev/uvesafb.c
index 73676eb..c592ca5 100644
--- 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;
 
-- 
2.7.4