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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Kees Cook" <keescook@chromium.org>,
        "Dr Silvio Cesare of InfoSect" <silvio.cesare@gmail.com>
Date:   Sat, 22 Sep 2018 01:15:42 +0100
Message-ID: <lsq.1537575342.239067717@decadent.org.uk>
Subject: [PATCH 3.16 48/63] video: uvesafb: Fix integer overflow in allocation
In-Reply-To: <lsq.1537575341.194909669@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.58-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Kees Cook <keescook@chromium.org>

commit 9f645bcc566a1e9f921bdae7528a01ced5bc3713 upstream.

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")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/video/fbdev/uvesafb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/video/fbdev/uvesafb.c
+++ b/drivers/video/fbdev/uvesafb.c
@@ -1059,7 +1059,8 @@ static int uvesafb_setcmap(struct fb_cma
 		    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;